Same issue here, slightly different. I have 2 differents IA levels, one normal and the other for demo purposes. The demo one unloads and everything goes on fine, but unloading the normal one hangs the BP execution flow as you said 
Same issue here, slightly different. I have 2 differents IA levels, one normal and the other for demo purposes. The demo one unloads and everything goes on fine, but unloading the normal one hangs the BP execution flow as you said