Still having this issue after the Definitive Edition's release. PLEASE fix it, it makes playing this co-op with my boyfriend incredibly frustrating. I am playing as Lohse and my dialogue is being skipped for my freaking quest line.
The NPCs, controlled by us, have a forced (continue) option to make it go to the next player in these dialogue, please patch it so that it simply does so for player characters too. Easy fix.