On another Tapatalk thread
JamieZ was the key to the answer of my question:
Subscribed is adding a thread to your list to watch.
Participated is when one posts a message(s) in the thread.
So, I have figured out that I have a number of threads subscribed to, that I have not posted in (lurking), and for this latest series where I posted the previous two messages, I was not subscribed to. I just tested this on the PC and via Tapatalk and see how it works now. So, all is good and hopefully this will help out another inmate on the site.