Suddenly one of my custom post types stopped working properly. More precisely, I have a custom post type called Apps where I have a few posts. Everything was working properly until I've created a new taxonomy using a plugin, then I've imported about 2-300 terms using an array in functions.php and then I've created a custom template for that taxonomy. Right after, the Apps posts couldn't be accessed anymore - even if nothing changed to them, the URL doesn't work, I get a Page Not Found error.
I reverted back to the original settings - delete the new taxonomy and terms, disable plugin, but I still get a 'page not found' error when I try to access the Apps posts.
You can see the behavior on this website.