Related news block in taxonomy term
It looks like the block disappears because no content is returned by the view. You're filtering for both a taxonomy term id and a node id, while only a taxonomy term is present in the url of a taxonomy term page. Since there are no nodes that match the criterium 'no nid' there are no results. I believe this should work if you use only the taxonomy contextual filter. (This is if I'm understanding correctly what you're trying to do).