Unfortunately there is a reset bug with both these cards. Someone here is working on a kernel patch to fix it but I think it’s still a wip. There’s no problem using the Vega on the host. However, the 5700 will have issues when restarting the VM.
Here’s the details -
Also, if you’re using a distro on kernel 5.2 it’s best to upgrade to 5.25 or greater as there were some virtualization regressions that got patched. There were also some problems with systemd and Ryzen 3000 processors but I believe those have been patched as well.
Last but not least, if you’re going for an X570 motherboard I’d suggest going for one that has a bios update w/AMD Agesa v1.0.0.3abb or later if you can as you may run into problems with IOMMU otherwise. At least I did on my X570 board with 1003a.
TL:DR get the latest patches yo. 