SOLVED – the issue was the WordPress block editor failing to load a core JavaScript file called undo-manager.min.js. Without that file the editor cannot start.
- Connected to the site over SSH and confirmed the asset files on the server are healthy.
- Reproduced the 404 from the CDN and proved it was a cache poisoning issue, not a code or database fault.
- Purged the cache directly inside Cloudflare for the affected paths.
- Purged all caches inside Kinsta, including the site cache, object cache, and Kinsta’s edge CDN.
- Bumped the asset version hashes so any stale references are forced to refetch a clean copy.
