Lightroom randomly replaces new Imports with older photographs

Hi all,

Lightroom Classic regularly chooses random photos which show up correctly in the Import window, but as soon as I click import, they are replaced (both the JPEG thumbnail and the full size RAW file) by a random older photograph from my Library.

I have tried renaming the files, copying them from other places, importing them again, and always get the same result. If I open the Raw files with any other program, I get the correct picture, but Lightroom Classic will only show the older photograph it has somehow linked to.

If I create a virtual copy in Lightroom, the correct image briefly shows up in the thumbnail, and is quickly replaced by the older file.

This is incredibly frustrating, as it happens for 1-2 photos with nearly every import (100 photos on average), and often they are pictures people are waiting for.

I also find it very frustrating that there is no way to directly contact customer support for a product I'm paying a monthly fee for.

Any help would be greatly appreciated. I'm hoping someone else has had this issue and figured it out. I've attached screenshots of me creating a virtual copy, where you can see the original picture on the right being quickly replaced by the older one on the left.

If not, any ideas for a Lightroom alternative?

I'm using Lightroom Classic (v. 12.0.1) on a MacBook Pro running MacOS (v. 12.5.1).

Many thanks in advance for any help.

Stephen