FYI
"I was having a problem with this, too, but figured it out. Skip going into developer settings.
Go into the Bluetooth settings section
connect the WH-1000MX4 if they are not already
click the gear icon next to the WH-1000MX4
You third option should be a turned off "LDAC" flick the switch and you're going to be in business.
The once greyed out "Bluetooth AUdio LDAC Codec: Playback Quality will no longer be and you can select an option or leave it on Auto."
https://www.reddit.com/r/sony/comments/jwxmv5/ldac_and_dsee_extreme_with_1000xm4_and_samsung/