I have found that the percentages are pretty accurate when averaged out over the course of all my games.  However, the rolls in this game are truly random, which unfortunately means that, even at a 75% chance to hit, you can have a string of just bad luck that seems to stretch out forever.  I've had entire fights where almost every roll seemed to be a miss, or my high-dodge people got hit every time.  Unfortunately, that's the nature of luck, and you'll find that in a long enough time frame (think 100+ battles), the percentages are accurate. 

This is one of the times you need some data. Get like 100 (at least) swings with hit percentages.

But the percentages are accurate from what I've experienced. 

But that's the thing, I'm aware of that concept and kept an eye on it. I guess no one else is experiencing this so maybe I'm just having a really bad streak of luck like some suggested. Not surprising, RNG has never been my friend.

Thx for responses guys. Least i know there isn't any hidden mechanics.

Man...I often have it where a lone strong unit is a hair's breathe away from dying and all I need is one more hit against it to finish it off. I move my strongest guy into position and before swinging say to myself "watch me miss", and then swing and it MISSES. This has happened to me soooo many times.

lol. bit of a realist (pessimist) at heart.

I actually could wind up helping contribute data collection here, as I started what I intended to be a tutorial to my playstyle using a custom sovereign with "Beastlord" profession ... its winding up being a long play-through.  I have 11 hour-ish sections thus far, and what the heck, I'll just keep going.  The early chapters especially are not very good quality, but I should be able to re-read the percentages, record them and note if they resulted in a hit or miss, crunch it through a spreadsheet or somesuch when I finished with the game.