MacBook Pro. No sound internal speakers after disconnecting Bluetooth devices

Hi. I have a 2015 MacBook Pro running Catalina 10.15.2

The internal speakers work fine until I connect a Bluetooth device then if I disconnect the internal speakers no longer work.

It doesn't matter what the bluetooth device is I tried it with different wireless headphones.

With previous OSs I used to restart Safari but now I must restart the computer to get this fixed.

Anything obvious to try?