First of all, let's distinguish between ritual cannibalism and starvation cannibalism. The first is a cultural ritual with various rules and norms and is done for a variety of reasons. Starvation cannibalism is self evident.

There were occurrences of ritual cannibalism in the New World. The Wari of South America were known to practice ritual endocannibalism. That is, consuming a portion of a dead member of your kin or tribal group. This was thought to allow the dead relative/friend to live on among the active community. There have been reports of other groups practicing this sort of ritual cannibalism in Mesoamerica and in North America (Texas and the far Northwest).

Much of the evidence is sparse and inconclusive and highly controversial. So controversial that in 1979, William Ahrens wrote a book called The Man Eating Myth in which he argued that because there was simply no verifiable evidence (first-hand accounts) of cannibalism in the New World, the practice likely did not happen.

New World archaeologists have always thought that starvation cannibalism, like the Donner Party, probably happened throughout prehistory. Butcher marks on human bones have suggested cannibalism at a number of sites, but the evidence just wasn't conclusive. One might expect it to happen anywhere under the right conditions. That has been the case during historic times. Many, including Ahrens cited above, have suggested that starvation cannibalism was likely the only practice used by Native Americans.

However, in 2000, archaeologists excavating an Anasazi site near Mesa Verde in Southwest Colorado found incontrovertible evidence of cannibalism including butcher marks on human bones, human residue in food containers and compelling evidence of human muscle residue in a human coprolite at the site. Several other sites, in the same time period, about 1000 year ago, show some evidence of cannibalism. Analysts have concluded that this was not a case of starvation cannibalism (see Bryan Bilmann's article in Social Violence in the Prehispanic American Southwest. Deborah L. Nichols, Patricia L. Crown University of Arizona Press, 2008).

So your answer is yes, it happened, but likely very infrequently. And a to a large degree it was as an attempt to fend off starvation. It was never rampant from a comparative perspective.

Anthropologists have every right to be cautious on this question. This is a very loaded subject and careless discussion has great portent to perpetuate the 'native as barbarian' mythology frequently used in colonial practices of "othering" native peoples. But, generally speaking, anthropologists have been fairly balanced and thoughtful on this subject.

Now with regard to the assertion that mainstream anthropologists hid information in an effort to be politically correct, thats just bullshit. You will find an abundance of published articles and books on this and related subjects dating back to the late 1800s. That is how our discipline makes information known - they publish it in peer-reviewed journals and books. And it is because of this record of publications we can put to rest assertions that anyone is trying to hide anything.