Please download our latest version (v2.2.6) which has just gone live today. If you are still having this issue, please do not hesitate to contact us!
If you are with 2.1.10 and cannot sync steps with Fitbit, this is a known issue and we are working on it urgently.
In the meantime, can you please list your device model and operation system version in this post? Also can you please try to sync again after midnight of your time zone and let us know if it starts working again?
We are very sorry for any inconvenience caused and thank you very much for your patience and support!