"No actions"

Can someone explain to me what is happening to characters who despite no visible status effects have "no actions"? I get to select them when it's their turn but cannot perform any action at all, the thermometer thingy starts completely empty. Specifically, I have noticed this in the Nulb ambush fight against Rannos and Gremag.

 

getting ambushed can certainly leave you surprised and while you are surprised then you have no time left but to pee in your pants while they whack away at you

 

I recall the casters there cast various debilitating spells, I think Bestow Curse might cause this. Not sire if it has status indicator.

 

It lasts for over three rounds in a row, and started in the middle of combat (after confusion wore down, to be precise), so surprise can't be it.

I've definitely noticed them cast Bestow Curse, that might be it then. Annoying that it doesn't show up anywhere. Between the various CC spells they dish out it's hard to know exactly what's going on without relying on the status effect display.