Steps to reproduce the issue.
Send Eder to the Eyeless Hammer surrounded by the tentacles (on the left side). Attract their attention. Flee. You are now stuck in combat.

save and output log:
https://www.dropbox.com/s/jbbqpzwhx2roxbl/combat_glitch.zip?dl=0

Hey Suen,

 

Thanks for bringing this to our attention. I have written up a bug and added it to our database.

 

Thanks a bunch!

I have the same bug, but I experienced something else on this exact point.

 

I tried to pull the Eyeless which is surrounded by tentacles towards my group, away from the tentacles, so I could kill him.

I failed a few times as the AI seems to "resist" pulling and the Eyeless returns to his initial position. However, at one point, he did move towards me. We fought normally and suddenly he returned back to his initial position. I sent Eder, my only standing group member there, he hit the vessel but he did not receive any damage.

Animations had stopped showing by the way. 

I decided to find out how far this would go. So, I scratched the Eyeless towards its death. Each time it reached "near death" status, it healed itself. 

The tentacles did nothing all the time. Just stood still. So I attacked those instead. They eventually fell, as these don't have an ability to outheal the damage.

In the end I moved Eder towards the cave, where there are 2 more Eyeless who also did not attack.

At that point my entire group was resurrected. I walked back, met my group, and combat ended. 

Rested, saved and the Eyeless are unbugged now.