Ryan,
With no change, the updated Protostar for Joomla4/5 it's not working in JCE... The style drop-down list remains mud :-/
https://www.joomlatema.net/free-templates/protostar-template-for-joomla-4-5.html
If I use Protostar outdated template from Joomla 2 or 3, I do get styles listed in JCE.
Style is outdated, not that fine with responsive aso... So wanna move to latest version from above link as output is much better
If I name the style (using FTP) as what is named in JCE settings, I do not see my personal styles.
But I may mix this style defs and Joomla's as I can read it should be named user.css... as if name my style user.css, I can see my style. in JCE...
As a bad boy...
I use the old template designing the pages (setting my personal style on DIVs as I can use the drop down list), and then, move to the new template from Joomla, and as a magic, I can see the results... (I set both user.css and my style as defined in JCE setting)
So, from Joomla, style seems to be properly defined.
Please point me out the mess am doing !