For the tags, from my testing this is broken right now and we've started an investigation, so thanks for flagging.
I did some poking around and I believe in your case the blocker was the Advanced setting about only getting notified on new discussions and not replies. I took the liberty of turning this on momentarily so you'll get notified for this reply, but then you can choose whether to turn it back on. You might have received a double notification too, please disregard that as I was checking another quirk I noticed. That setting seems to "default" back to "new topics", I'll look into it.
I appreciate you looking into it. If you could, please keep me updated.
For the blogs, your best bet would be to go to the games you're interested in, and manually follow each one from the blog page.
Unfortunately, I think this may be another area that's broken. I'm following a few blog pages and I'm not being notified (via Email) whenever a new blog is posted. A recent blog for The Sims was just posted on The Sims Game Info Hub and I wasn't notified about it.