Ever since I picked up Tristan and dismissed Niles to put Tristan in the party, Niles has completely disappeared from the Incognito.  I can still add him to my party when I leave but he's missing from the ship and so I can't talk to him there or do any of his interactions.  

Has anyone else experienced something similar?  Have you been able to fix it?  I've tried various things like putting Niles in my party and then sending him back to the ship but it doesn't work.  I would try restoring to before I got Tristan and sending Niles back before the dialogue to add Tristan to the party but I didn't notice the problem for a long time and I'm waaaaaaaaaaaaaaay past that now.

Please help!

Yeah, I just realized that, he was gone since I got Aza onboard, the only character I like, the one that is not annoying, is the one that is gone from the ship.

Just as you, he can be added once I leave the ship but he doesn't have the normal convo options they have in the ship.

Yeah it seems to happen when you pick up a new party member but like I said I can't go back and test dismissing him from the party to pick up Tristan because I didn't notice right away.

Niles returned briefly for the post Golden Ridge debrief but as soon as I left the Incognito / transited to a different planet he disappeared again.

I can live without him on the ship I'm just thinking this is going to screw up something down the line, particularly any companion quests for him.