Sony XZ1
When you connected just your smart watch (which can be used as headset) via Bluetooth and having a phone call, screen will off automatically if you brining mobile to your ear.
Its OK.
BUT in case you additionally connect another earphones whether plug in a wired or connect wireless ones and then disconnect them, then the screen will not automatically off when you bring your mobile to your head during a call.
As a workaround disabling and then re-enabling Bluetooth will help.
But its annoys. Could somebody help with this?