I'm using OMV on armbian on a Helios64 and I recently upgraded to buster and got everything set up the way I like it and the system found my RAID and last night, I had everything working... and then I rebooted.
The first problem was that the RAID wasn't mounting under File Systems category. after manually fixing this, It's mounted under:
/srv/dev-disk-by-id-md-name-helios64-helioraid/
but not under:
/export
In other words, NFS is not working, correct?
I've tried restarting NFS in the OMV web UI but no change.