It is a known bug with us, indeed, when burned calories disappear if the device was shaken or dropped during charging or if the time in your phone was changed, such as if you moved to a different time zone or if the time was changed to or from daylight saving.
In the latter case, if the clock was moved forward, you can restore the lost data if you change the clock back to show the previous time and then restart the smart band, the app and sync the band with the app. If the clock was moved back, however, the data are permanently lost and cannot be restored.
Our technicians are aware of this bug and will try to fix it in one of the upcoming releases. We apologize for the inconvenience!
If you have additional questions, please email us at gobe@healbe.com We will be happy to help you!