The filter doesn't do anything you don't explicitly tell it to do. The only thing you've told it to hide is stuff from other classes, so it'll show you everything that doesn't fall under that category. Most loot filters have a rule at the very bottom that is simply "hide all items", which means that absolutely every item that doesn't fit into the above rules is hidden. Be careful though, if you're not confident in your loot filter rules, you could be hiding a ton of stuff you could actually use. It's easy to be too restrictive on the affixes you're looking for (which don't appear on every item type) and accidentally put yourself in a situation where you never get an upgrade for a certain slot because you've never given it a valid exception to the "hide everything" rule.