Hi vinko.nicolas.kolar,

Thanks for reaching to us.

Please remove Custom Attributes https://prnt.sc/-nyDYuBfayM6, re-add via selects https://prnt.sc/vuuvqzfT0FjC

You can refer to documentation for more details https://xtemos.com/docs-topic/variable-products-and-swatches/

I created demo product, you can take a look https://staging.otakusale.com/produkt/test-product/

Regards,