only simple products possible

After Update to the new WooCommerce Version 4.4.0 we cannot change the product typ.
When we change to variabel product it turns back to simple product after save.
We have this problem with old and new products.
We also canno change to other product types, it always turn back.
The products seems to still are working for the customers but we can’t make any change in the datas, especially in other languages.
In other languages we cannot access the variable data like price and amount, because we can’t change the product typ.

https://www.schnitzer.eu/de/produkt/bio-focaccia/

The page I need help with: [log in to see the link]