Top ranking (top X% this period) in the Activity tab is not displaying very first time when you are visiting to the SE site which you were not visited after the new profile page UI change.
To reproduce this, visit any site's Activity tab (you have 200+ reputation on the site) which you are not visited recently, this display issue in the main and per-site meta.
Steps to reproduce:
From the top bar site switcher select any site which you are not recently visited.
In the site, click the reputation from the top bar, it will navigate to Activity tab, there very first time inside the Reputation box the top ranking will not display.
If you are navigate to other tab and come back the Activity tab again, the ranking will be display.
Screenshot for reference: