Well, for one thing: The tag must be spelled properly. Just as you accidentally typed @#MaarketFriday at the end of your last comment, someone might have not spelled it correctly in a post.
If the tag is correct, though, then I don't have an answer. We could certainly ask the devs for Ecency and PeakD, though, and maybe get some insight.
The misspelled tag is not usually that big a problem because although it does happen it's not that often. Except by me, obviously.
I would say most are probably with Ecency or when the post under the China then i have to call it up through that post. I know I'm not making any sense but I guess I'll try to look into it. Thanks so much and my apologies for not proofing my own writing. Have a great day!