An issue has been brought to my attention seemingly revolving around the steam overlay being enabled. I'm having trouble completely replicating it, but this update should hopefully help prevent it from occuring.
Still, I would recommend avoiding opening the steam overlay often, and saving before doing so. If something does get corrupted exiting the game and loading that save will fix it.
Part of this effort sees the "select previous character" function mapped to ctrl+tab now, rather than shift+tab as it was before.
Thanks again for playing!