I created a new page which is assigned a custom template. When I visit that page's url I see what appears to be the default page layout (not my template) and the admin toolbar shows options pertaining to media (ex: Edit media).
After some head scratching, I deduced that somehow that url must point to a media item. I edited the page slug and "bingo" the actual page appears just as expected. When I visit the original url (from the first slug) I see the same media item.
Bottom line: It appears that coincidentally the page and the media item share the same name, and this was somehow causing WP's wires to get crossed.
My question: Can someone help me understand how/why this happens? Does wordpress create magic permalinks to everything in the media library (other than their location in wp-content/uploads/...)?
Note: The media item was uploaded normally into the media library (not FTP into the root directory, etc)
Yes, in WordPress you cannot have duplicate slugs/categories/taxonomies/tags. So if your theme allows for media files and permalinks to have their own page and the slug is the same as another one, it will usually append a number to it because the database does not like it.
media slug "example"
page slug "example" will not work since that slug exists already , if done in the admin it will automatically change the slug to "example-1".