Sync issues

Hello everyone,
So in the Lightroom web, it shows I have around 7000 pictures in the "Sync issues", and to sync them I should open the Lightroom App.
The problem is the sync has stopped because it shows the error "Some items invalid". When I go to see which pictures have the error it says it couldn't find any pictures. And when I try to also see the pictures that should be syncing, it is empty too.

How can I solve this? What happened to the pictures? They show in the web