ReadyNAS 312 not putting all new files onto the vault

ReadyNAS 312 with 2 4T drives.

Purchased in March, just installed due to an unfortunate delay. Especially unfortunate that the unit has been running for only 2 weeks but the 90 days of free support are done.

We upgraded from an ancient ReadyNAS Duo V1 solely because some newly created files would not be placed into the online vault.

I was specifically told this was only because the unit was so old, speculation was it was running out of memory to track the files.

We switched over to the 312 early October. It is doing exactly the same thing, some newly created files appear in the vault, some never do.

Am not sure if changed files are going to the vault.

Mode is continuous.

Has anyone ever seen anything like this? No one had when we had our Duo, so I'm not hopeful, but any suggestions will be appreciated.

TIA

Dave