We sometimes experience the same issue... Any feedback?
What type of permission does the end user who is adding the CSS have?
I ask because we had the same issue. It turns out that CSS is one of those things that Jive struggles with unless you are a system administrator. The way we got around it was to add the CSS to a space by uploading the CSS file (not just adding the raw code) using the "Manage Files" option. Once it is uploaded the user can ref the CSS:
Only issue is when the user wants to change the CSS 48 times in a one week period.....
Hopefully this helps!
Thanks for the solution, right now I send the HTML/CSS file to the super admin/moderator (don't know what the highest rank is), because it works when he does it.
But this is a good alternative.