Are you trying this from prism central? Which version of prism central? Does it work directly from Prism Element (do not access prism element via prism central to test, do it directly).
A slightly different version is in place, but the following workaround has already been applied: https://github.com/ktelep/NTNX_Scripts/tree/main/CE/ahv10_commercial_workaround
Now that this workaround is functioning correctly, https://github.com/ktelep/NTNX_Scripts/tree/main/CE/ahv10_commercial_workaround (modified AHV 10.0.1.1 4831838208k → AHV 10.3.1.1 268435456k), as a result, the UEFI + Secure Boot boot behavior has improved from "Operation failed: Internal Exception." to "Guest has not initialized the display (yet)." I tried obtaining the launch options from the AHV /var/log/libvirt/qemu/ logs. (However, -m size=16777216k,slots=240,maxmem=268435456k is forcibly overwritten to -m size=16777216k,slots=240,maxmem=128G inside qemu-kvm-frodo.)
From this, is there anything we can infer about "Guest has not initialized the display (yet)."?