My unarmed was stuck at 3 for a while, despite me fighting semi-frequently with just my fists. I don’t get any exp at all, whether I fight against a petty zombie or mi-go’s and zombie brutes. Kinda sucks since I’ve really wanted that counter-attack on brawling. :<
You can train it by using a weapon like punch daggers or brass knuckles. It is a known bug.
It was fixed in the recent versions.
I’ve been having the same issue and I’m running the most recent experimental.