Windows 10: Windows 10 doesn't recognize an external USB drive

I have a 4 TB external USB drive, which works as expected in File Explorer, but when I try to configure the Windows 10 Backup utility to use that drive, the utility does not see the drive. It does see two other USB drives, but they are too small to be used for backups.

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USB (all) not recognizing external drives

Up until a few hours ago my USB recognized my external hard drive. Now it doesn't. Shows up in Device manager as Other devices not a drive. Tried 2 different USB's (didn't recognize), tried a different external drive (didn't recognize), took external
drive to another Windows 10 PC and it worked fine. I have shut down and restarted but did nothing. The USB ports work on other devices, printers, postage scale, wireless mouse fab but can't get it to recognize the drive. The usb port makes the "noise"
when you plug/unplug it and the external drive has power from the usb. Any advice?

 

I can't access my external hard drive with Windows 10....

The computer doesn`t recognize the external hard drive. Help!

 

help. USB drive isn't assigned a drive letter.

Any usb flash drive I plug into my computer isn't assigned a drive letter. The physical drive shows in the "safely remove hardware" but it doesnt show up in disk management. I have tried to populate the volume thru the safely remove hardware properties window and it does pop up in the list but it doesn't stay there. This isn't a format or assign a letter problem. It's more complicated then that. Maybe one of the services needed for usb drive management was disabled? Suggestions needed. btw external usb harddrives work fine.