There's a bug where a campaign gets corrupted and is no longer joinable in co-op.

I've attached the point of corruption, a good save and the very next quicksave which is corrupted: https://drive.google.com/file/d/1_YyqnS9Dj8wIdh79JcsEMNPJjodsjrjv/view?usp=sharing

QuickSave_23 is loadable and co-op partner can join

QuickSave_24 is loadable and co-op partner receives error `Joining failed: The session has no controllable characters available`. If I load a good save and have partner connect, and then load this save, partner sees "You were kicked" and I see "Player left".

This was reported in https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=682633 and https://forums.larian.com/ubbthreads.php?ubb=showflat&Number=687355 but from the copypasta email response the users received it probably wasn't read properly.