Saving to Desktop Slow - "Working on it"

Hello,

One of my users has a Windows 10 laptop and is having problems saving to his desktop. Basically, he goes to "Save As" something (an Outlook attachment, for instance) and it gets stuck on "working on it" for a few minutes. It does eventually come up. Also, the Desktop under Quick Access shows no files.

Now, from what I can the problem doesn't occur when he's trying to save in any other location.

Any help would be appreciated.

Lately - for the past few days - I have been having the same issue when trying to open a new directory. Even moving up one level in the directory tree starts the same "Working on it.." delay.
Windows Defender claims there is no malware, as far as I can tell no new browser add-ons have been installed
sfc /scannow has been run a couple of times, without any change
Rebooted a number of times
I am at my wit's end and very frustrated