GVT is not correct for you hardware. Issue is that you need i915.force_probe=7d55 in the i915.conf in modprode.d.
The two plugins sort this. Use intel GPU top not gvt.
https://github.com/unraid/webgui/pull/1938
Temp fix is to run
sed -i '/webGui\/nchan\/vm_dashusage/d' /var/run/nchan.pid and refresh page until rc2 is released.
Does your array auto start or do you manually start the array from the dashboard?
I have been able to reproduce this, have added a fix which I hope will be in the next release.
Can you run this in a browser.
Replace IP with your IP, change to https if required
http://ip/sub/vm_dashusage
This should download a file can you send.