What exactly do you mean by “never gets seen or pick[ed] up anymore?”
I notice that your March 20, 2017 post has about 40 tags, and the April 3 post has about 30. Excessive tagging may be part of the problem you’re encountering. The first “possible explanation” in the Missing Posts section of the Tags in the Reader support page says:
You are using too many categories or tags. In most cases, there’s no need to assign more than a handful of tags per post. If you use more than 15 tags and categories (total), your posts will not appear on tag pages (because you don’t want to see irrelevant content showing up there, and neither do we).