Copy pasting from the reddit bug thread http://www.reddit.com/r/projecteternity/comments/30nuxn/patch_1020508_bugs_megathread/
• Description: Unable to change party members. Despite making sure that the party member is not busy on a mission, it is impossible to add new party members to my party. I've tried party management both at the stronghold, as well as various inns across the realm. Attempting to leave a party member at the stronghold, and then rehire him does not work either. In addition, the 3 inactive party members appear to teleport into various areas in the game, where they provide the idle dialogue from staying at the Stronghold. Kana does seem to appear in the same area as the player party, but does not actually join the party.
EDIT: It seems like the bug only affects some party members. In my case, these are the party members that I have not been using during act 2, as well as the final stages of act 1. Savegame[1] **EDIT#2: Scratch the last part. It seems quite random who is able to join or not. Had some luck adding the Dwarven Ranger, (but only her, out of 5 selected ones). But after changing things up again, she is no longer able to join.
• Steps to reproduce: Remove and Hire party members.
• Expected result: Dismissed part members leave party, new party member joins party.
• Observed result: Party member leaves party, no new member added. Can not reinvite old party member.
• Reproduction rate:10/10.
• Game Edition: Steam
I am effectively stuck with my current pary, and can thusly not add Kana to finish the dungeon beneath my stronghold.