tried to block com.sonymobile.mx.android but always result:false
no offence intended but are you using the command correctly / getting the syntax right?
Has pm block worked 'correctly' for you with other packages?
When I do it, I have my adb files in a folder imaginatively called "adb".
I use the command line, from within that "adb" folder, and issue the following command:
adb shell pm block com.sonymobile.mx.android
The response should be "Package com.sonymobile.mx.android new blocked state: true"
Using the unblock command should result in a similar response, except ending in "false".