Probably having the same issue I am.  On entering Tactical it's like all units automatically get a -1 Move or Speed (forget which), if the result is less than 1 (some fraction) then your unit is stuck and becomes a punching bag.

Basically, what happened is this...

It was early in the game. I had picked up a combat hero with minimal armor and a bastard sword, having about 22 Combat Rating. I got a quest to confront [named Darkling] and another Darkling. So, I did. They had a total CR of 6. I double-checked it, happened again with this hero.

The battle began on their turn, so they approached. It totally skipped my turn, each time, until they managed to papercut my unit to death.

I don't remember everything...22 attack, 5 or 6 defense, and 12 HP. The little Darklings did 1-2 damage each turn. I think 2.

Normally, I'd be OK with it. But the fact that two Darklings with less than a third of the CR of my champion were able to pwn me so easily is more than a little irritating. Especially since my Sov teleports far, far away, and I don't want to engage in any battles.

EDIT: In short, I never had a turn to do anything. It was enemy turn, followed immediately by enemy turn, ad infinitum.