I have virtual PaloAlto firewalls in Azure. The firewalls are fully discovered in Solarwinds, and all the interfaces are listed, with commits, etc.... But, the interface traffic is showing all zeros. My hardware PaloAlto firewalls show data for the interfaces, just missing all the VM information.
Orion Platform 2018.4 HF3, NCM 7.9, NPM 12.4, NTA 4.2.3, NetPath 1.1.4
Have you done an SNMP walk of the PA and compared it to a physical? Ours work..but we have had a lot of issues with PA-VM code levels. I am not 100% but my suspicion would be on the PA not putting out values in the first place, and solarwinds just displaying what it knows.