Finally giving this game another go as I have the energy and there have been some big patches. Still very fun but my enjoyment of combat is severely hampered by UI wonkiness. Sorry if this stuff has been brought up, didn't see it listed.
There are a lot of problems with 'linked' turns/'linked' initiative. What I am referring to is how, if multiple player-controlled characters have their turns in a row, you can select and move any of them in any order. In theory a nice QoL thing to let you do cool tactical stuff. However, the game is REALLY BAD about figuring out who still needs to act in this case. If you don't notice the linked turns and just take one or two char's turns then hit end turn, the game will almost always skip the turns of one or more of the chars who had 'linked' turns but hadn't moved or acted. Please either fix this bug so that the game never ends the turn for a char unless you specifically select that char and hit end turn, or (at least in the meantime) provide an option to completely disable linked turns and force all characters to take their turns one at a time in initiative order, even if multiple PC-controlled chars are able to act in a row. Seriously, having to painstakingly micromanage my chars to ensure their turns don't get skipped is very annoying, I would rather have to move them all 1 at a time.
Pathing is sometimes different from what the game shows. For example, I hover a unit's path and see they will move down a ladder (or fly down the wall by the ladder) and then attack the goblin at the bottom, so I click, and instead the unit goes running off through a door and then ends their movement in a different room nowhere near anyone, because apparently they were actually trying to run out the door of the building and go all the way around it instead of taking the ladder/flying down like the pathing display showed. This is obviously really annoying as it can easily screw up your plans/force a reload. In a similar vein, it can sometimes be really difficult to get a character to just walk up and attack an enemy instead of trying to run around to the side or behind them, taking opportunity attacks all along the way.
I would really love to have a grid system instead of this free distance based one. No idea if it is possible to do this, I am guessing it would require a bunch of different coding than currently exists. My main issue with the free movement system is that it can be really hard to 'eyeball' and see if there is room for a character to fit into a space in melee with an enemy when there are other characters or obstacles nearby. For example, I position a character by an enemy and think there is room for another character to get to that enemy, but it turns out there was just a hair too little space and I wasted a bunch of movement/turns. Or, even more annoying, a (medium sized) enemy hits a char in melee, but on that char's turn they are somehow both out of melee range and don't have enough room to get into melee range because of an ally on one side and a random rock on the other (yet the monster could still attack them!). A grid system would solve a lot of this. Assuming that is not possible as an option at this stage, maybe you could add some kind of melee position display that could be optionally turned on and allow you preview characters in melee positions at specific points around an enemy that will then allow you to see which positions around that enemy are available/will be available if your character moves to the previewed point. Like how it shows an outline of the character in melee when you have a melee attack selected and hover over an enemy in range, except it also displays the other 'available' positions around that enemy as additional outlined chars, showing what spaces remain available if your character goes to the currently displayed space.