Veeam installation keeps failing on "creating zfs"

trying to install Veeam software appliance on a truenas system

The installation is from an ISO of an app specifically designed to run in a Linux VM- it has quite specific installation requirements. I had a test appliance running yesterday, but killed that instance to reinstall into a different dataset.

The VM runs fine, the iso boots, starts to install but then hangs every time when its:

“creating zfs on dev/mapper/datavol-veeamrepo”

any ideas?

i have recreated the VM, changed the ZVol locations, uploaded a new iso. there are no obvious failures- it just hangs….

Running latest Truenas os on a 6day ugreen nas, i5, 64gb of RAM, mirrored 1tb NVME Apps drive, RaidZ1 across 5 12tb WD Red discs.