Notes from the layers in between.

The ticket says the page is wrong. Someone has already opened the theme. Someone else is disabling plugins. Both are reasonable moves, and both assume the application produced what the browser received.

Often it didn't. Between WordPress and the visitor there is a cache, a reverse proxy, an edge network with its own rules, and a browser holding a copy of yesterday's HTML. Any of them can serve a response WordPress would never generate right now — which is why the same URL can be broken for one person, fine for another, and fine again for the first person an hour later.

The cheapest thing you can do before touching code is establish which layer produced the bytes. Request the URL with the cache bypassed. Compare response headers. Check whether the edge is varying on a cookie, a country, or a device class nobody remembered configuring.

If the response changes when you change the path it took, the bug is not in the theme.