I created a community yesterday, and added some tags in the settings:

I also added some wikis to the new community, and used some of the tags in them. When I start typing the tag, it wasn't offering suggestions as if they were already available, but it still let me add them:

However, they don't show up at the top of the community page.

Since they were added last night, I don't think it can be an indexing issue. What else could I be missing here?