Unrealistic misses ( eg if you often miss 4 times in a row what should have been 75% hit ) are different issue from my OP point here - I also have those "unrealistic" strings of misses sometimes, and it could be tied to low hp or bosses as you mentioned. It is important to note that even perfectly fair RNG have chance for such misses, but in example I gave it would be less than 1 in 250 chance. So for it to happen to me twice in few hours is strange - and I would agree that some misses are unrealistic.
I suspect that, in some scenarios, game does not show correct hit chance %. But this is different issue from my OP "misses", where even when misses happen exactly at rate shown by tooltip, they are too often for my liking.
Also, unrealistic skill checks are different issue both from unrealistic misses and from my OP realistic misses issue. It happened to me several times, sometimes in positive direction (eg, I got 20 three times in a row when rolling on well in Blighted Village that lead to spider cave ), and sometimes in negative direction - most recent example is that I needed to reload 10 times (!) on "confused Ox" or whatewere its name was ( in barn just next to Zhentarim hideout entrance barn ) , where it has two skill checks, one for 5 and other for 6 ... should have been fairly easy. And yet, I got roll result under 6 around 10 times in a row ( had to reload 7 times, three times out of those I passed '5' requirement with exactly 5, and failed on '6' requirement, and four times I failed even on first '5' requirements... two of those were roll 1 ). Probability for that in 'fail' d20 roll is around 1 in 1 million (!!) , and that is just probability to roll under 6 for 10 times in a row - in my case I was rolling mostly under 5 too .
What I think is that some skill rolls are intentionally rigged, to make them either much easier or much harder , regardless of what roll target says. Personally, I do not think that is good approach - why not just show '1' as roll target on village well, and 18 as target on Ox ? But ,again, this is different 'misses' issue from my OP about regular combat misses.
