Please be aware that when you edit a post and remove tags or add them it will take time perhaps even a couple of days for that post to appear under the Topic pages assigned to the post and it will appear in order of its original datestamp.
Note that display of posts on the most popular Topics pages is randomized as there are so many being published each and every minute of the day.
I have been here for 6 years and I can say with confidence that my blogs have never received a significant flow of traffic from the Topics pages. The traffic received ahs been negligible at best. It's Google that sends significant traffic to blogs and Categories/Tags are not required for SEO purposes. Search engine spiders are focused on the keywords in content. Revisitng Keywords and Tags