Lightroom Classic Shows up in Task Manager but won't open

Hi,

Long time (frustrated) user of Lightroom Classic. I have been havign sync issues between LR Classic and the Cloud again. I often upload photos via LR for iPad then later sync these raw images to my PC. Anyway, I updated to the latest version and my sync stopped working. I left it several hours. In the end I decided to close LR Classic and restart before trying again.

Now when I go to launch LR Classic, nothing happens. No splash screen. No icon. Nothing. The only thing I can see is that the task manager has an entry for LR Classic which is using 25% CPU and anywhere from 2 to 11 GB of RAM.

I have tried:

Alt Shift and resetting preferences.

Using a backup file to load from

Removing the lock file

Removing the whole catalogue

Loading an older catalogue (this says I need to upgrade the catalogue but crashes on that screen)

Nothing seems to work. Once again I am paying through the nose for a product which constantly fails me! Any assistance much appreciated.