Speakers don't work after connection with bluetooth device

Hello,

When I connect my FP5 to a bluetooth device, this works fine. However, when I disconnect it, the speakers don’t work anymore. The mediaplayer (Spotify in this case) still shows that there is a connection to the bluetooth device. Even when I turn of bluetooth the speaker doesn’t work, and the mediaplayer still shows the bluetooth connection.
I’ve observed this behavior with multiple mediaplayers.
When I get a call the speaker is just working fine…

Any ideas?
Thanks!
Pascal.