Two things that just happened to me on the second level of the Engwithan waystation:

 

- combat would not stop after killing all enemies:

Room with all the Imps, one of them hit my player character with their -1 empower charge ability, which would not wear off after combat, preventing the end of combat. At least I assume that was the reason. No counter was showing with the status effect, waiting for around half a minute didn't help. Reloading and killing the imps again solved the problem.

 

-unkillable skeleton summon:

In the northwestern room with the named Engwithan Saint (Xakoras?). The mummy priest thing came alive, and while it was still summoning his animats and skeletons, it already died. Most of his summons died with him, but one skeleton remained. It then was untargetable (didn't even have a selection circle), but continued to attack and deal damage to my party.

I encountered a similar issue in the Xakoras fight. Xakoras died before all the summoning animations had finished. Most summons were instantly destroyed but one animat ended up in a strange state.

It had no selection circle and I couldn't interact with it in any way (untargetable, AoE attacks had no effect).

It also had no collision detection. I ran over to the next fight hoping that triggering it would fix the half-summoned animat (it didn't), and the animat ran after the party, walking on air in the process.

The animat itself couldn't really do anything. It would move next to party members and attempt to use abilities but none would resolve.

I've had combat not end sometimes on ship battles. I thought it might be because I'd loaded a save from the start of the fight, since it autosaves at the start of ship fights.

Two things that just happened to me on the second level of the Engwithan waystation:

 

- combat would not stop after killing all enemies:

Room with all the Imps, one of them hit my player character with their -1 empower charge ability, which would not wear off after combat, preventing the end of combat. At least I assume that was the reason. No counter was showing with the status effect, waiting for around half a minute didn't help. Reloading and killing the imps again solved the problem.

There is another imp, in the next room, sitting in the corner but belongs to the same encounter.

Probably imp AI do not know how to open doors, or he is jut shy.