WDDMService.exe writing massive amounts of data - HDD not attached


I’m a big fan of the Passport series and have 3 with me constantly.

However, I’m struggling a little at the moment. I have none of my USB drives attached yet the WDDMService is writing 1MB of data a second nearly. I’ve taken this snapshot of the 3 WD services running:


Have any of you had the same experience and if so, is this normal? Is it intended?

Many thanks

Cheers, Pete