Nozix, if you can provide me with the exact ASUS X570 model you have. If you still have the STX II card in your system, please take a screenshot of devices and their IRQ (guide
here) and upload it somewhere. Only those (PCI) entries are important and make sure that all (PCI) entries are included in the screenshot.
If you can return the ASUS motherboard, then go for a Gigabyte X570, as Gigabyte motherboards generally don't have these issues with STX II cards. If you can't, on
this page you can find some things you could try.