Make sure to follow all steps while applying the hotfix.
You mention you had issues from upgrading 12 to 13? It is not recommended to ignore those errors and continue with applying hotfixes. It might be something that's only solvable by rolling back your upgrade and DB and start over the process.
Make sure you follow all the steps in the upgrade process.
Some of the pagebuilder issues could be caused by something like IIS caching, macro signing but also wrong urls, or permissions between the domains.
Can you share the errors you got from 12 -> 13? Did you get an upgrade succesfull event log message?