first off, ONTAP9.4 (and P1) is not officially validated but recognised to work. Anyway,this combination introduces a quirk but it doesn’t break the solution. Backup and restore are working. During the restore operation, you need now to select the ESXi yourself.
The quirk can be observed in the snapshot browser section. Host column reports <unknown>, State either Application/Crash status
I did remove and add again the storage that’s where it begins to become interesting
As soon you add the storage, the host column gets fill with your esxi fdqn (if you did configure your reverse DNS) but later returns to unknown as soon the state is returned!
I am unable to determine if the u3a or the ONTAP 9.4 is behind this. The other systems I manage still run U3 and are on ONTAP 9.3 branche.
While doing the last video, it went a step further now, one volume shows both come as expected, but the rest shows only the state information.
Case is open, videos have been submitted to the support with the case #03184929 with complete logs of 2 systems (fresh install/second one upgrade U3 to U3a)
Happy hunting

Oli