groupped product connections disappeare

Hello.
I have a problem: my groupped product connections disappeare every day!!!

For example: all this groupped products 30 minutes ago included many simple products, but now almost of them are empty.

https://moon-store.ru/%D1%82%D0%BE%D0%B2%D0%B0%D1%80%D0%BD%D0%B0%D1%8F-%D0%BA%D0%B0%D1%82%D0%B5%D0%B3%D0%BE%D1%80%D0%B8%D1%8F/alchemia/

https://www.ads-software.com/plugins/woocommerce/