I moved a site from Joomla 2.5 -> 3.6 recently, and some of the URLs in the site changed.
For one critical URL I used the Joomla redirect manager to create a redirect, and it worked as expected.
However, within a few days the URL began to return 404 errors again. I checked it in the redirect manager, and it is still there, and still active. But it's not working.
Is there anything I can check to figure out why it was working then stopped?