Autoptimize is a caching plugin that can cause a conflict with any of our plugins that contain the Thrive Architect editor (at the time of writing this is Thrive Leads, Thrive Architect, Thrive Ultimatum, Thrive Quiz Builder, and Thrive Apprentice).
Go to Settings -> Autoptimize
Add "editor.min.js" to the list of scripts to not optimize:-
You can then click the button "Save changes & Empty Cache"
You will then be able to go ahead and edit your content without any issues!
A Note About Performance
This will not affect the performance of the front end of your site. The script "editor.min.js" is one of our scripts that is only loaded when editing content in the back end of the site.