Same issue here. I am using HTC U11 and my BT headphone is Sony WH1000XM2. Sometimes the player can be controlled using headphone and sometimes cannot. My Sony headphone comes with a mobile application that configures the headphone and shows information about the headphone. What song is being played will display in the app. When the Bluetooth control is not working, the song current playing will not show up in the app. Thus, I guess the issue may be related to the metadata transmission or AVRCP. Look forward to seeing any solution.