I got the same after getting Volo to camp. Nobody actually has a conversation pending, yet the message pops up saying someone wants to talk.
At least I think it is caused by him. I try to talk to him and the dialogue above his head pops up saying; "Not now"/"Later", so he is stuck and cannot be talked to.
I had the same issue with Volo and then again with the Tiefling Bard at the party. I assumed it had to do with me playing a bard as well.
