Volume Warning on Disk Useage

Last weekend I ran Disk Test on my:

NAS314 4TB x 2

ReadyNAS Pro 2TB x 2

ReadyNAS Ultra 1TB x 2

all running OS 6.6.0

Since then I have had aletrs every boot on the Pro:

Less than 30% of volume media's capacity is free. NETGEAR recommends that you add capacity to maintain current performance levels. Continuous protection snapshots will be deleted when volume free space is less than 5%.

But according to the Admin Page:

and

 which indicate plenty of free space.

 The Disk Test only emailed me that it started and a few hours later that it ended. I have no indication of faults or errors. Frankly, I'm not sure what it tested, found or (may have) corrected.

Any suggestions, please?