Hello,
It seems to the topic map disappeared because you are using the topic as banner topic.
I tested it on my test site.
Now this is a banner topic and the topic map disappeared.
If I remove it from banner topic than the topic map appear again.
It looks like topic map only shows when the topic is regular but when you set the topic as banner topic it will change it from regular to banner.
Now this topic is regular (not using as banner topic)
If I use it as banner topic the archetype-regular class will change archetype-banner.
In here we can see topic map is only shows if the topic archetype is regular.