Sorting Products Big Issue

Hello team,

I am facing a serious problem with the classification of products.

I have a product that belongs to more than one category, for example the red balloon product belongs to 3 categories (balloons category (A), birthday category (B) and latex category (C)).

For some unexplained reason, when I go and change the classification of the red balloon in the balloons category (A), the classification of the rest of the products in the other two categories is broken.

Thanks in advance