I read through this thread and didn't see anything mention this. If it has been brought up, I am sorry.
Anyhow, sometimes upon zoning/reloading my UI or having someone join my group, I get a big bx taking up most of my screen. This has happened for as long as I have used Pitbull, not just in the new version. Also, it is unpredictable. I haven't seen any correlations between zones, classes, levels, or anything else. Here is a pic.
Same problem here. I've had to go back to ag_unitframes as much as I hate to do so. I love Pitbull and the customization available with it, but if it doesn't work for me, it simply doesn't work. I might have to simply start trying to isolate the problem. Make sure that it's not a conflict with another addon and then go from there. It just makes it difficult when the problem is completely random. I can go for several days without it happening then all of a sudden it happens and I can't get rid of it no matter what I do.