Products with combinatons not saved after updating prestashop from 1.7.6 to 1.7.7.6

[mickine]

Hello together, after updating from 1.7.6 to 1.7.7.6 I have some trouble saving products with combinations. If articles are old or new created makes no difference. Quantity changes aren't saved and editing product price with tax doesn't work properly. If I try to edit the price, its set to 0. Articles without combinations are saved properly. Debug mode doesn't display any error. Php-Version is 7.3 Any idea how to solve?

Thanks and greetings from germany