Thanks for the tracked threads link, which I admittedly have not used.

Sometimes tracked threads do not float to the top with new posts for me. It could be an issue where I am unintentionally tracking a subthread. Also, sometimes not all posts in a thread show up. If I relog later they are back.

I assumed it was due to flaky software or servers. Could be a problem at my end. Either way, I don't have that problem with other software and have grown to prefer the functionality of the newer software. To each his/her own.