Adobe Reader not opening Deduplicated files if Reader is already open

Hi,

Unusual issue, but Adobe Reader will not open files for one of our users. I've tried:

Updating to the latest version

Reinstalling Adobe Reader entirely

It will open if:

It is not already open

You click and drag it into Adobe Reader

It will not open if:

Adobe Reader is already open, and you try to double-click it or right click and select open

The files will open on other peoples machines just not this one

No errors are given

No events are logged in Event Viewer

I'm a bit stuck.

Machine is Windows 10, latest build.

The files are on a shared drive

Thanks in advance