If this is the scenario you’re dealing with, open the Sony Headphones Connect app on your mobile device and check if Google Assistant or Amazon Alexa is enabled. Make sure the touch sensor control function or Voice Assistant function is set according to the way you use the earbuds. There are cases where these functions are enabled, only the side with the touch sensor control function set to Playback control can be used by itself.  You can assign Playback control to both sides, but the full functionality is only available on the Right side.