Does anyone know if they figured out this bug yet? I am using Steam, just started not too long ago (about May 2016) and just ran into the bug. All files are up to date. I tried re-installing to no avail. The bug seemed to start just after I did the Svef Den in Copper Lane. When I went up to release the home owner, and came back down after jailing the wizard, the wizard's stuff was on the ground. Then I could no longer remove party members. Sometimes it would just ignore my changes, other times the party members were on the world, but did not show up in my party. It seems to be when I remove Durance, and I am sick of being stuck with these guys. I want Kana back;).
I would love to upload a save file, though I think it is on Steam's cloud.