Problem with Primary Category in breadcrumbs

Hello,

I have a problem with the categories: In some products a wrong category is shown in the breadcrumbs: https://www.littleyou.me/product/mp-denmark-cotton-rib-tights-oeko-tex-col-848-dark-aqua-green/ The primary category is Girl, shown is Boy.

This product also is not shown on the category page for girl, but for boy:

https://www.littleyou.me/produkt-kategorie/fashion/girl-2-to-10-years/socks-tights-girl-2-to-10-years/
https://www.littleyou.me/produkt-kategorie/fashion/boy-2-to-10-years/socks-tights-boy-2-to-10-years/

In the girl category 2 items are double:

https://www.littleyou.me/product/mp-denmark-ankle-socks-oeko-tex-clematis-722-rose-glitter/
https://www.littleyou.me/product/mp-denmark-ankle-socks-oeko-tex-clematis-749-yellow-glitter/

The Girl category page shows 15 items, which is correct, but 2 are double and two are missing.

This is very confusing. Tried everything, checked all products twice, reset permalinks, CSS, cache, inactivated caching plugin.

Does someone know this problem?

Thanks for your help!
Dirk

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