Hi
I had this problem in the past with another site and I have no idea how it got fixed.
When using the Simplistic theme on EB5, I have several CSS issues, like modal windows that never open, save buttons that disappear. This is the one that I was using when I upgraded, so I'm not sure if this is the cause of the problem. I tried to recompile the LESS files and had no effect.
The other problem that I'm seeing, but it seems that it's for every theme used, is that I can't change the author, the wheel keeps spinning and never finds any user.
thanks!