New
#21
OK. I did see the 'Device in use' but later it worked flawlessly multiple times.
Looking at Event Viewer/Applications I see a couple of warnings as below:-
The application \Device\HarddiskVolume1\Program Files\Windows Defender\MsMpEng.exe with process id 2056 stopped the removal or ejection for the device USB\VID_1516&PID_1603\93E41C6E20914A881D1308E9.
So, at least in my case, the holding prog was Defender.