after I tagged a post with a subject with no hashtag, with one that is related, any of the following subject replies didnt tie in to the 1st subject , even with the initial post with same subject tagged.

That's because although both posts are inside the same hashtag, they have different subjects (with the first having no subject at all from what I understood).

So, as far as I could see, nothing unexpected :)

Cheers,
Marcio AKA Starboy

Sent from a galaxy far, far away.