I had the same problem, I thought you had to push the "sync with fitbit" button at the bottom of the nutrition tracker, but it turns out you don't. If you just enter in SP, it will automatically sync over to FB (and if you click the sync button on SP, it pushes everything over again, causing duplicates on FB).
I also found that it doesn't like it if you delete things from SP. I accidentally entered one item twice, then deleted the extra item on SP, but it did not delete it from FB. So it's a little fickle, but if you enter everything exactly perfectly all the time, then you will have no problems! Ha!
| current weight: 167.0