I am trying to display all markdown documents without a tag. However, the result does not produce any search result. Leaving the tag field empty does not show files without a tag.
Maybe I misunderstood you. Let me rephrase what I understood: You’re looking for all items in a database that are not tagged but are not tags themselves - correct?
In this case, it is sufficient to set “Kind” to “any document” and “Item” to “not tagged” (see screenshot).