I think it always happens in the same situation, though I can't be 100% sure as I pay more attention to the skills being used and the enemies than the visual placings of my team.
These three things have all been happening when the glitch occurs.
- It is the 1st character on my team.
- They have a shield active.
- The character is Sorawind.
I'll let you know if I notice it happen in any other way.
Also, did you drop the % chance of Soulmancer Freeze spell working from 50% to 40%, or did I do something to make this happen?