Some users have run into syncing issues where no matter what they do, recent activities just won't send/resend to Runkeeper.com, even with a great internet signal. If you run into this issue and you have already tried resending your activities, there's a couple troubleshooting steps you can try that might get those activities with red triangles sent to our servers.
1.) If you have a category (race, speed work, stroller run etc.), photo, tagged friend, notes, or smiley face (feeling) selected for those activities that aren't syncing, try editing them and removing that information, then try saving again. Some users have had success resending their activities this way.
2.) If that doesn't work, you should be able to fix this by writing down all of the info from that oldest activity that hasn't synced, so as not to lose it, then follow the same steps as before, but instead of selecting save again, select "Delete Activity." After you've deleted it, go to the next activity and try saving to resend again, doing so for each following unsynced activity. If it works, great! Now all you have left to do is re-enter the activity info you deleted, which you can do by using manual logging.
Hopefully, one of these workarounds will get those activities sent to us, but definitely reach out to Support if you're constantly hitting this issue and we'll let you know when everything's fixed!