The video shows that Lightroom sync activity is going on, has that now stopped? And if so, is Lightroom still not doing anything when you try to export? If not, can you repeat the screen recording but this time use the other Grid (called the Square Grid) as that shows status icons which the Photo Grid does not.
Have a look at the "Deleted" album, checking for any deleted images which are still trying to sync and thus have become "stuck"....this can happen if an image is deleted before it has had time to fully sync. If you find any, delete them manually to see if that clears the blockage.