Thank you, the builds were fairly recent but the update to the hosts worked. USB and GPU passthrough are currently working together now. It did break my windows 11 vm due to no tpm/secure boot but it was a reghack to get it to work anyways

I was going to create a new post dealing with this issue. So I'm going to bump this one. I am having the same issue. USB and GPU passthrough works great but not at the same time. I have not looked at the logs yet other than the quick error at the bottom of xcp-ng center

xcp-ng 8.2
center 20.04.01
hardware hp z620 with updated bios to the latest

guests:
windows 10
windows 11
ubuntu 20.04

all have the same error