Most folders in share have disappeared

FreeNAS-11.2-RELEASE-U1

I was accessing files on my mirrored pool from MacOs Catalina 10.15.6 when the files I was transfering appeared then disappeared on the server.

I jumped into Freenas GUI to check for reported errors - no errors.

The server reports that the disk is 46% full, but the shell returns about 2% of that.

The iocage jail was on the pool, and is no longer working.

I have a backup (a little old now) but I need to know what's happened to the server - if it's a failed drive why is it not reporting an error? If the software has failed (running on usb) then surely there should still be an error reported? I don't want to replace the data on the pool until I know what's what.

Please see attached screenshots of current content and backed-up content, and reported size of content compared to what Freenas see.

Thanks

I'm running a scrub right now.