Network connectivity may have been disrupted while the row was in progress, specifically at the end of the workout.
Your workout statistics for any given Row are recorded and reported only when you exit back to the menu. This could either be at the natural end of a row, or if you choose to end it early.
This means that If your network either disconnects or is disrupted at the time when a Row exits no information gets uploaded to the server for purposes of leaderboards, team racing, etc.
What steps to take:
We find that the most common cause of this symptom is due to momentary network cut-outs, either due to weak Wi-Fi, Interference, or other connectivity issues. If this happened to you just once or twice, it is likely not cause for concern. If you find that this happens frequently over weeks of rowing, you may want to try Troubleshooting Wi-Fi Connectivity in your setup.