Please provide a step-by-step process of how the bug can be reproduced. The more details you provide us with the easier it will be for us to find and fix the bug:
1.place melee thralls
2.equip weapon of choice
3.lure enemy to them.
4.will approach and use fists.
This also happens with Archers and after combat they often don’t return to there positions and get stuck.
Tested this 19/01/2019 using an mammoth.