The dungeons I filtered by are missing in the 'Results' tab

I selected a Level 70 generic, protection spec Paladin.

Step 1, Selected ‘Mostly TUF’ and Talents.
Step 2, Kept everything by default, except for check-marked ‘No badge of Justice’ and filtered ‘Dungeons’ only.
On ‘Customize Strategy’, I selected ‘Crush and Crit immune’.
Clicked on the ‘Find Best in Slot’ button and I noticed that I am seeing a lot of items from ‘Black Temple’ and even an item from 'Badge of Justice. I did see one dungeon that I selected ‘The Mechanar’ was there, but no others.

Did I make a mistake somewhere?

Best in Slot will always allow gear that the loaded character has equipped. If you start with one of our generic characters, it will have some higher level gear already equipped.

Try starting from a character with no gear equipped – export your character using our addon. If you don’t have one of the class you’re looking at, just make a low-level character and export it. Alternatively you could manually exclude the items already equipped on the generic character.