Add product to category

[Omnimar]

Hello,

We are using Prestashop version 8.2.0 for our webshop and for some reason, the category of products jumps to empty (See uploaded image). When the category is empty, we can't add any category and therefore the item is not visible on our webshop. We re-created a couple of articles because of it, but still the category of the ‘new’ items jump to empty again and we need to start over again and again and again. Does anyone else experience this issue or know how to solve it, without having to re-create a product over and over again?