In less than 48 hours the Viltrox engineers solved the issue on the NF-Z adapter ring with an updated camera firmware.
I've sent them a full doc of what and how the errors appeared and the ring and camera behave.
I suppose they will put it in the site's official downloads later.
Meanwhile, I can share with you mine.
www.dropbox.com/s/onad4ribjj1mwrw/NF_ZV1.30.bin?dl=0
Tested with Z30:
Nikkor AF-P 70-300 5.6E
Sigma 150-600C