Im getting the same bug, cannot switch people out though weirdly enough it only happens when i try to recruit Durance. I have not played it for a very long time and decided to go back, i had Durance in my party but lost some of my later saves, i figured due to my moving them from one harddrive and doing something stupid probably. Anyways decided that a few hours of lost progress should not stop me, so i tried to recruit Durance again. However he disappears from my screen as soon as i have recruited him, he is however still on the map as Durance, however it is a ghost version of him (see link). When i get back to my stronghold i suddenly have 2 of him, one normal and one naked, however i still cannot go anywhere since i get the voice that says "you do not have your entire party" or what ever keeps popping up. So know i have 2 useless versions of Durance, i have tried loading a previous save, and i can dismiss and recruit as much as i want until i try to recruit Durance, then the same thing happens. I have tried deleting and reinstalling the game but that does not help so i think its my saves that are screwed, however i do not know how far it goes back. The dude with the robe and hat is fake Durance btw. (I have not used any mods or cheats what so ever).
http://steamcommunity.com/sharedfiles/filedetails/?id=731276083
http://steamcommunity.com/sharedfiles/filedetails/?id=730619568