Hi, this was a bug I ran into in RTWP mode but am running into again in TB more severely.
When I enter into Cavern of Xuar Tuk-Tuk to rescue Mother Sharp-Rock, several (though not all) of the hostile xuarips are untargetable. They place in the turn order once combat starts and can make attacks against the party, but the party cannot attack them or select them in any fashion. AoE attacks don't seem to hurt them, but triggering environmental traps do.
Strangely, once I've killed all targetable enemies, turn-based combat stops, but the remaining xuarips attack the party and do damage as though it were RTWP. I still cannot do anything except leave the cave to avoid their damage. Mother Sharp-Rock will not leave until these xuarips are dead.
The save is too big for your system, so here's a dropbox link: