I had the same on different websites when updating....
Before migrating i really looked closely if there were any errors given in the update screen...
After fixing all the issues i made another backup (just to be safe)...
When I had this same issue i reinstalled the backup in a test environment and exported all the pages seperatly...
Then updated a fresh new website with the latest pagebuilder and then imported all the old pages into the new websites...
Not the way i wanted it to work but hey, it worked for me so maybe you can use this while we are waiting for all the bugs to be gone :)