You know best about your WordPress installation, so you are the right person to solve the issue.
Make a note of every minor changes you made to the WordPress core files, plus those on themes and plugin customization.
The Kitchen Sink Visual Editor is finally back.
What was tried:
- Disable plugins
- Disable themes
- Disable CDN
- Disable editing capabilities
- Enable debug
- Finally reboot your server, lucky if you are running the site via VPS just like this website.
Make a summary of things to try to troubleshoot as mentioned here
I spend 3 days figuring out what the actual issue was and finally there was the solution.
Let me share what I did so far to solve this issue.