The only thing close to this is the oft-repeated suggestion that Hittites were unknown except through the Bible, but that's based on a couple of remarks back in 1857 by F W Newman and T K Cheyne, both which suggested that the biblical mentions of the Hittites was unhistorical.

The bible doesn't mention Sumer (unless you count Erech -> Uruk which is a city), but Sumerian was used (badly) all the way down to the first century BC so I'd be surprised if it wasn't known, even if there's no particular contemporary historian writing on it. Herodotus certainly mentions Egypt, Babylon, and Assyria. Akkad is part of the same group of Mesopotamian civilizations that devolved into Babylon and Assyria, and it was spoken and written until the 1st century AD.

Bonus claim I heard: There are documents of the Hebrew enslavement, the record lies with the Israelites and even Egyptians but Egyptians are known to destroy documents at times.

If they're destroyed, how do we know what was on them? Egyptian administrative documentation is poor in a number of places for a variety of reasons, but that's not the same thing.