WD Drive Utilities stuck at 90% for more than 12 hours

Hello. I have a 3TB My Passport Ultra. On October 11, 2018, Time Machine started failing on the drive. The drive is almost full. It has around 100GB left and only 56GB are needed for the next backup. But Time Machine stops a little while after starting saying that it cannot copy the files to the drive.
I already checked the drive with the Mac OS X drive utilities (I’m runnning High Sierra) and no errors were found.
I downloaded the WD Drive Utilities. Ran the SMART test and passed. Ran the Quick Drive test and passed. And 24 hours ago I started a Complete Drive Test. This last test has been stuck in 90% for more than 12 hours now. I see the drive light blinking.
Is it hung? Should I stop the test? Should I wait? How much longer?
Thanks in advance for your help.

Hi damaini,

There may be some process of My Passport Ultra still running in the background apart from Complete Drive Test due to which test is not getting completed. You should wait till the process completes.