[Fifa rant continued]
Turns out it wasn't the share button! I just won again after PK's and FIFA crashed right before the results screen.
Seems it's a problem with FIFA, and I'm guessing it's from restarting the challenge within the match. If I go back to the main menu after the match and relaunch from there its fine, but if I restart the challenge during the match it seems to always crash right before the results screen.