Portal Front Side Editing not reliable

Hi All,

Is anyone else having a battle to get Portal Front Side Editing to work as advertised? Rarely, a simple text edit will work ok, but most of the time it doesn't, and an error is thrown like this:

The error ID seems to be randomly produced - it changes every time.

Any had this issue and been able to make it go away? We're on the latest portal version (9.1.2.22) and the portal solution is up to date.