Restoring cards dosen't work

Before I installed the ‘image occlusion enhanced’ add-on, I synchronized my cards by uploading them to Anki Web.
After that the installation all but the last card I had learnt were gone. When I wanted to use one of the backups, I found that they were all ‘empty’ and didn’t have any cards either. (Wich is strange because I created the cards weeks before the last backups and also synchronized them regularly with Anki Web)
I don’t know if this could have anything to do with the installation of the add-on…?
Is there any chance you can restore the cards anyway?
Thank you for your help

I haven’t heard of any other reports of that add-on causing such problems. You don’t appear to have an AnkiWeb account at the address you’re writing from, so either you were using a different email, or you had not synced.