Yes, I suspect there's a new problem with following in patch 4. I've never had issues before, but now Halsin keeps stopping following my party (as others have said about Shadowheart, the rest of the party will follow him). The issue is resolved if I save and reload, which is good, but does mean I can't submit a save game with the issue to Larian.
I'm trying to find a pattern, and thought it might be something to do with wildshape. But if there's a similar issuw with Shadowheart then possibly not.