Group: Awaiting Activation
I think the disk is indeed failing.
My thought (sounds better than outright guess) is that the device has a problem but the error being reported back is not the usual one associated with bad cluster(s) such as a CRC error and therefore isn't being recorded by Reflect.
CHKDSK may be doing things differently and may allow an operation to complete whereas it times out of otherwise fails in normal use. You could download and run the manufacturer's diagnostic which often are much more thorough in checking disk operation or just cut to the chase and replace it.