It's not a bug. When you dismiss some of the companions, they don't all stay in Fort Joy. I just had the pleasure of finding a "mini cheat" by doing the Water Well quest with the extra companions I probably won't be using to get extra epic belts/rings. Sebille, The Red Prince, and Fane all go to Amadia's Sanctuary. Fane is located on the beach above Kerban's smithy. I just happened to need to go there to start the assault on the magisters and found Sebille and The Red Prince by mistake, so I hoped to find Fane there and I did, lol. You're welcome, have a nice day, lol!
Also, for some reason, when I rejoined each member, I got 5600xp each time, so it's bonuses all around, lol!
