Bluetooth problems headset (Sony MDR-10RBT)

Since yesterday, I have been experiencing problems with my bluetooth headset from Sony (MDR-10RBT) on my 2015 MBP Retina, 13".

The headset shows as being connected, but when I play any music (streaming, or local), the sound does not come through to my headphones.

The headset does work correctly with my phone (Android device).

Another bluetooth headset (Bluebuds X) I have does work correctly on my Macbook.

Info of the computer (partly in Dutch, but should be clear enough):

I'm running OS X 10.10.5.

Modelnaam: MacBook Pro

Modelaanduiding: MacBookPro12,1

Processornaam: Intel Core i5

Processorsnelheid: 2,7 GHz

Aantal processors: 1

Totale aantal cores: 2

L2-cache (per core): 256 KB

L3-cache: 3 MB

Geheugen: 8 GB

That's about it I think... Anyone know what the problem is?

Modelnaam: Ma

Geheugen: 8 GB