Can't save Frontpage layout as menu item type

Hi,

When I want to select the "Frontpage Layout" as a menu item I'm unable to save it. Also the backend page looks strange, e.g the dropdowns on the right. See screenshot.
I only have this with the selection of the frontpage layout not with any of the other easydiscuss menu item types. Also only the close button works.

I already deleted the cache, changed browsers, but all unsuccessful.
Does anyone know how to solve this? I'm aware that this issue is most likely not related to easydiscuss itself but to Joomla / another setting, but any help would be appreciated.

Thanks.