First and foremost, you've got to understand what it is that ancient historians mean by "records" of ancient Egypt. We do not, by and large, have accounting ledgers or encyclopedias from that time. They may have existed (well, probably not in the case of the latter) but they are gone to us. What we have instead are the objects that were left behind: sarcophagi, obelisks, the insides of the Pyramids themselves, and so on. For the same reason your local town probably doesn't have a statue on Main Street commemorating the time your country lost a war, these artifacts tend to be heavy on the wins and light on the losses.
There are also archaeological type artifacts such as the tools that were used during this time, the bodies of workers and the pharoahs, and so on, but those, too, tend not to come with instructions. As incredible as people are nowadays at extrapolating out nuggets of information from this evidence, stuff like "oh, in 3496 they lost a battle to the Assyrians" is just not going to appear in these records.
What we do have in the case of Egypt are long periods of time where there isn't a great deal of recorded history. For example, the First Intermediate Period was a time when the lights went out, so to speak. There's still a decent amount of information to be had from the period but nowhere near like what we have before and after. We can surmise from the way the art differed that there was a bit of a split in the empire during this 100 year period, but beyond that, it seems that a lot of what we know about this period of time is what folks said about it afterwards.
Add to that the fact that we've only been able to read hieroglyphics for about 180 years now and you start to get an inkling as to what we have to use.
As to the specific claims made by the Bible and the Exodus, there is just plain no way that several hundred thousand Jews lived in the Nile delta. There's simply no evidence for a group of that size. Some Egyptologists (notably Robert Breyer) think that the legends may be based on a group that was actually there, but if so they were orders of magnitude smaller than what is portrayed in the Bible and might be better referred to as proto-Jewish rather than actual members of the established tribe.