A couple of workarounds were found in a thread about this yesterday. Hopefully one will help you.
You can hit the spacebar to progress the dialogue. You don't get the visuals but you will get the full dialogue text.
Alternatively you can have one of your not dialogue locked characters kill one of the unmasked druids and combat will ensue (breaking the dialogue).
From my meager testing both work arounds had NPCs acting correctly after.
