Volto - can not edit home page (website content type)

I started to get in touch with volto and installed plone6 (from packages). Everything works fine "but" when I try to edit the default start page I can delete the existing blocks, but cannot add new blocks.

I have checked the behavior settings of the website content type - seems to be fine. I currently have no idea what i am missing.

see Why I am not getting an editable layout and add blocks option?

Thanks and omg :man_facepalming: