Ok, so I know about the "walk=freezing merc" bug, I also know that you need to blink or "teleport" (via portal or a passage underground) to unfreeze him. I played around with the act 1 and 2 mercenaries, sometimes they froze but it wasn't a very big issue, because it happened rarely, about once every ~2-3 areas. This is bearable.
BUT.
The act 3 mercs (I'm using a necrolyte) are a goddamn nightmare. They easily lock at least 2 times in the same AREA. And as an early bloodzon I have no other means of remedy than TP or going to a dungeon. As Median is more designed towards walking than running this makes them completely unreliable.
Now, I thought about it a little, done some experiments and I think it has something to do with the "avoid melee, go to safe range" mechanic of this merc. This would also mean, that act 1 merc would be more prone to locking than the act 2 one, and - wouldn't you know it - she is more prone to this (priestess or ranger, doesn't matter) than the act 2 merc (shapeshifter at least).
I know the locking happens randomly but it got me wondering - maybe something would change if act 3 mercs would get something like %chance on hit "Phasing" (teleporting them in a random place not far from where they are standing; it could even be a "dummy" teleport with 0,1 meters range), maybe it would refresh their logic every time it happens and at least reduce the chance of a lock happening?