I've got a similar bug with Wyll and I've reported it through the Feedback tool before. I can talk to him but can only tell him to "wait at my camp", which doesn't remove him from my party. At camp he has the same dialogue.
You know, in general I think a simple "party composition" UI (only available at camp) would go a long way as a QoL change and would also speed up the process even if companions aren't broken.
