Tabs not showing in the module with Joomla 4

Hi,

I've installed JUX Youtube Feed on a Joomla 4.2.2 website.

In the administration of the module, I'm not able to add tabs / groups (no "plus" button).

Could you please help?
Thank you!!

Dear @Jackie
I'm not sure whether to thank you or not. Although the backend problem is fixed, the frontend now shows errors "Deprecated: json_decode(): Passing null to parameter #1 ($json) of type string is deprecated in /home/harmoni2/nieuw.harmoniesimpelveld.nl/plugins/system/helix3/core/classes/menu.php on line 290" which were not there yesterday. Can you please restore whatever you did to make those errors disappear?

Edit: you apparently just enabled all error reporting which was on a lower level before. Excuse me and thank you for the repairs!