Internal speakers disabled when plugged into external monitor
When I plug my laptop into my external monitor, the audio output automatically switches to the monitor. When I then go back into my audio menu and switch my output device to "internal speakers", there's no volume. I've verified that the internal speakers are not muted and volume is maxed. When I switch output to the external monitor, it works normally again.
I want to be able to use the internal speakers in order to maintain keyboard control of volume and muting.
Hardware:
2017 MacBook Pro running OS 10.14.6
Anker USB-C hub
HDMI cable
Vizio TV
MacBook Pro 15", 10.14