Muffin Builder dont export or import (Doesnt work)

I started a new wordpress project with the Betheme.
I've the problem, that my muffin-builder don't work. When I klick on the button (at the end of my builder-content) export or import, nothing happend.
Even Pre-build-sites I can't export/import.


I can't find a solution for this. Please help. Without the option of export or import it is very exhausting.

Thank you!