Arkeia diskstorage issue

On one of our RA appliances the scheduled backups have stopped. Manual backups just sit when executed. Looking at it on the status screen it displays No Usable Data. I can browse the clients and the directories that were backed up but no files appear.
Have ~15TB with 9TB used. Have reindexed and checked the logs time and again, restarted the unit, powered off and back on with no luck. As the reindex runs the last part of the log message is is empty. RAID array appears healthy, though I’m uncertain how to diagnostics on it. Can write, edit and delete a file on the array /vol0/diskstorage .

Any idea would be appreciated to recover.