If you have more than 500 friends in the game, then your friendlist as well as requests from friends can be displayed incorrectly.
Recommended amount of friends in the game is not more than 500.
If you have more friends, please try the following:
Reinstall the application.
If the issue still occurs:
1. Clear your browser cache
2. Update Flash Player
3. Try using a different browser
If none of this helps, please address your request to the social network help desk.
Regards, Nexters Support Team