Thanks for the quick response!
Just to be sure though; I only just hired the Glanfathan Soul Hunter (about 1 day or less in game time). Was he supposed to leave so soon? I'm pretty sure he hadn't left yet when I updated to 2.0. If I remember correctly, the stronghold log also didn't say anything about him leaving.
For the first guest hireling, he might have left already, so there might still be a problem of a different kind, which you have pointed out.