Sync problems on iPhones

The first thing to check is whether your Pebble app is still connected and running in the background. Watchapps, particularly those running on Javascript, will not be able to collect and relay the data they need if the Pebble app is not running.

The best way to ensure this is to hard-close (http://support.apple.com/kb/ht5137) the Pebble app, and relaunch it . Check the top right corner of the app for the status, and tap it if it says “Disconnected Pebble” to re-establish the connection.

After this process you must request a sync from the LetsMuv app.

If you re-connect Pebble but the app still isn’t working as expected, please contact us.

It would be also very useful if you could send the incidence to Pebble ( From the Pebble app -> Contact Support )
“As per request of LetsMuv developer I’m opening this incident. It seems that DataLogging is not working properly since sometimes I need to force close Pebble App to start working again, but this will only fix the situation for a few hours/days. Thanks”