Can't change settings in Themes for Flamingo anymore


we try to change variables in Flaminog Themes editor for our custom template but alle variable boxes a grayed out and are not changeable (see screenshot). The user is in the XWikiAdminGroup is able to administer wiki and set permissions


Maybe we changed some permissions wrong? It was working before. By the way unregistered and registered users see the installed themes.

Xwiki version is 13.3 on Debian 10.9

Thanks for any help.