Solution : 

1. if you log out from the application then you need to scan the smart scale again. Check whether your smart scale is paired with your device or not. Kindly go to settings > scan devices

  2. if you are using the latest mobile phone (android pie and above) then for actofit smart scale app select don't optimize battery option from settings. (settings > Battery > select actofit smart scale > select Don't optimize battery) 

 3. set background limit from settings to allow background processes. (go to settings > search background process > set standard limit)

 4. Allow all permissions that are required  for Actofit Smart scale application.( go to app info > permissions > allow )  

 5. Install The Latest security patch / system updates if available from mobile settings.  

6. check your internet connection when measuring the body compositions.