Hello,
thanks for your response. We found a solution. After Migration for a WooCommerce 3.4.3 (yes we know, ancient 🙂 ) some database tables broke. We isolated 2 tables woocommerce_order_itemmeta and woocommerce_order_item and then proceeded to regenerate tables from the WooCommerce tools and it generated the two new tables. At the same time we exported the old data via PhpMyAdmin as CSV and imported the data into the new tables. The combination of new tables and data via CSV worked for us.
Thanks again for your efforts and for all your cool developments. Have a nice day 🙂
Best regard Lena
