How can a drive be full when there are 1.74 TB free?

I recently set up my 2 TB My Studio LX and configured it for automatic backup. The backup was performed and it said that I had 1.74 TB left on the front of the drive and on the “Backup” tab in the WD Smart Ware program. But upon checking the WD Smart Ware program I discovered a little yellow warning message saying the “disk is full”.

How can a disk have 1.74 TB of space left and be full? Doesn’t this violate some law of physics? And if not, what’s going on here?

Did you resolved this issue?