I am assuming the device is still paired. In settings under bluetooth do they show as connected for media audio or call only or both?
If you press the gear icon are both sliders on?
I should have added, what app or apps are you trying to control?
Most music apps have a place in settings where you can turn remote control on or off.
I use VLC for example and it defaults to allow remote.
My music app defaults to off but you can turn on remote control.
Naturally I don't use any of the same apps but..
They should all be in settings. My Podcast player specificly lists bluetooth settings but my music player just lists as headset controls.
In VLC it is listed under settings > advanced controls.
As far as the gear, did you try reselecting from the gear music app?
What couldn't hurt and may resolve some issues is Samsung. Grab yourself a refreshing beverage and a snack and go here..
scroll all the way down and in the middle is a box labeled chat.
See what they have to say for themselves.