I cam across an issue on my staging website where the file listing of the template editor is not working as it should. It flashes a split second when loading the page, but then the left column where the file listing should appear goes blank.

On my live website it works as intended and the file listing shows. 

To rule out any difference on the staging website, I made a fresh install on the staging site, using an exact copy of the the live version. 

What could be the reason for this behavior?

Please be advised that test URLs have limited support. Often if the file set and database are the same, it would be a server configuration item which is preventing it from showing. Looking in your browser console you may see an error. Often this comes up as mod_security when there is a display or save issue which is loaded over AJAX like this is. I would recommend reviewing your server/php configuration to ensure they are the same.

Thanks for that ultra-quick response and thank you for pointing out in which direction to check! I will have a look at it.

Edited January 13, 20223 yr by evcom
typo

Ok, got it sorted. The base url in the conf_global.php file was not yet 'https'. Using https solved the error (mixed content) shown in the browser console.  

Excellent! Glad to hear you found the issue.