From my understanding (being an undergraduate in a university program), the exact opposite is true. The real question you should ask is what topics is there virtually a consensus on amongst historians. Honestly, every claim I've seen one historian make, I've seen many others contest it. It's simply the nature of the field. To give you a few examples:
Who was responsible for the quagmire that is Israel/Palestine? Politically and religiously motivated questions such as this one lead to sharp divisions in historical academia. While this is murky waters and I will refuse to give my own opinion on the matter, one could make the argument for at least 3 candiates: Zionists, Palestinian Arabs, and the British. And there are others even who could further extend the answer to provide answers such as the Ottomans (who let Jerusalem go into a state of decline) or the French (who worked with the British to form the Sykes/Picot agreement). Or you could narrow it to specific people: Chiam Wiezmann, Arthur Balfour, Lawrence of Arabia, Husayn bin Ali, or Sir Henry McMahon.
Dates become very murky, particularly before the modern age. An example my teacher used when explaining how medievalists essentially have little to nothing to work with on many topics was a symposium she went to where the main question was the date of Beowulf's origin. You would think something like this would be relatively straightforward, but the opposite is true. Dates range from as early as the late Roman period all the way to the Crusades (granted these extremes have little support, but you get the idea).
I've also done several similar thought experiments with myself. Here's a good question to ask yourself: When did the modern age begin? Was it in the 1300s when the Renaissance began? Was it in 1453 when the Turks took Constantinople? Was it in 1492 with the discovery of the New World and the expulsion of the Moors from Europe? Was it with 1514 with the Protestant Reformation? Was it in the 1600s with the scientific revolution? Was it in the 1770s with the American Revolution? Was it in 1789 with the French Revolution? Hell, was it in 1815 with the fall of Napoleon? Any one of these answers is valid, depending on your field of study, and there is no consensus amongst historians.
Hell, let's take a question that is much simpler on the surface; when did America begin? While the consensus tends to be 1776, I've seen (and made arguements) which place the origins as early as 1756 (the beginning of the 7 years war), and as late as 1789 (the development of the Constitution and the election of George Washington).
I could go on an on (I do similar thought experiments all the time), but I figure my point has been sufficiently made.
TL;DR: Anything is pretty much a complete free-for-all, including even the simplest questions, and I'm curious where you think there is a lot of consensus
I was thinking of a different way to phrase this question: "In your area of history, what is a hotly disputed or contentious claim that has significant/valid support on both sides? " As another comment points out, things like "when did the modern era start" can be disputed easily (I think). However, a post the other day outlined the dispute over the USS Maine explostion and it demonstrated that there were valid historical arguments supporting the various theories on how the explosion occurred. I would think that these kind of fact disputes about "did it happen?" are fewer and more interesting than the more open-ended essay prompt, like, "when did the renaissance start?" or "what caused mussolini's rise?"
While I think it's true that every field has its disagreements (and that the very writing of history is an exercise in challenging consensus), there are also those that are more divided than most.
For example, estimates as to the number of victims of Stalinist repression in the 1930s has for decades been a particularly fraught field. Soviet studies in general has always been a bit rough and ready - a product of political stakes during the Cold War, limited data availability and the early influence of émigrés - and by the 1980s a strong faultline had developed between the 'traditionalists/totalitarians' (Pipes, Conquest, etc) and 'revisionists' (Lewin, Fitzpatrick, etc).
This gave rise to an explosive argument in the early 1990s when the first archival repression figures were published. These suggested that the levels of repressions had been significantly below the higher range of estimates (although, interestingly, roughly in line with Lorimer's population estimates from the 1940s). This was the trigger for a pretty bitter round of polemics from each camp. At times it got pretty bitter, with accusations of Stalinist apologia and moralising being thrown around. It's only in the last few years that anything resembling a consensus has started to emerge on the number of Stalinist victims (tending towards the lower estimates), and even then there's still much debate about 'responsibility'.
In short: historians of the USSR love playing Genocide Olympics as much as anyone else. It's rarely a particularly constructive or polite conversation.
I've just been reading Ian Morris recently, and he opens up with a discussion of the central question in his book, which I think is in some ways the mother of all questions in this day and age, which is why Western civilization overtook Eastern civilization in the modern age.
He quotes a very wide range of authors with a very wide range of answers to this very important question. There are people who argue that there are cultural / institutional factors in favor of the west (which could be anything from Protestantism to Athenian democracy to Enlightenment philosophy or anything else), cultural factors working against the east (confucian hierarchy, family structure, imperial bureaucracy, the social status of merchants, and so on), geographical factors working for the west (the atlantic ocean, proximity to new world frontiers, proximity to coal), and random chance events that happened to hit in the late 18th, early 19th century.
Morris himself seems to take a fairly cyclical view of history which mostly runs counter to old eurocentric school of thought. I've personally also read Pommeranz and Gunder Frank's books, which definitely also dispute the sort of received eurocentric wisdom on the subject I used to get in (western) school, as espoused by, say, Landes. The Morris book is very recent, so I would be surprised if overwhelming consensus has been reached since then.
Unless there's been some major change in the last few years that I've skipped over- there's many many many competing theories about who the hell William Wallace actually was. The one that seems most likely to me is the son of a minor landowner who happened to be in the right place at the right time but there's many more. One of the ones I like but don't think is likely is that he's an English longbowman mercenary who defected.
History MA here--I've always looked at history as a story that changes depending on when it's told and who's telling it. My area of research was Modern US, so aspects like dates and locations are a little less debatable depending on the subject, but every historian exploring said topic is going to have a different slant, a different idea of what is important, even if they're building on what was written before them. It's trying to piece together the why and the how and why it matters in a way that makes sense given the data at our disposal. And even then, some new theory or piece of data will emerge years later and make old theories obsolete.
There's probably thousands, but here's one only because I was just reading about it:
Large stone circles across the Middle East.
No one knows who built them or what their purpose was.
They are at least 2,000 years old, made of stones piled just a few feet high that sketch a circle about 400 meters (1,312) feet in diameter across the landscape, reports Owen Jarus for LiveScience.com. These circles were discovered in modern times by aircraft flying in the 1920s, but have recently gained more attention through the work of David Kennedy, a researcher at the University of Western Australia and his long-term aerial photography project documenting archeological sites in the Middle East.
“It was 60 years before anyone noticed [the circles] again, and only in the last 10 years have we started flying over every bit of the country looking for more,” Kennedy told The Washington Post. He and his colleagues have found 12 circles in Jordan, one in Syria and two in Turkey. An ancient Roman road cuts across one, so they likely predate the Roman Empire.
But researchers still have no idea who built the circles or why. The walls are too low to keep in animals, and their precise shape wouldn’t be necessary for pens.
Another History undergrad here. If you get the book, "The Quest for the Historical Israel" you can find a great example of disagreement among historians. Two historians debate different understandings of how Isreal arose in the ancient world, looking at archeological and biblical evidence. Very interesting.