No sound from a MP4 source

[Dave N]

Hi
When I select a source such as an MP4 and play it in OSB, the video plays as normal but I cannot monitor the sound it does not play in my headset.
I can record vocals over it as it plays and the original sound plus vocals are there on playback, but I don't hear the source sound when recording, what am I missing?
Ta in advance

 

[Lawrence_SoCal]

Advanced audio properties - default is Monitor off (ie if you recorded in OBS, your OBS recording would most likely have audio, it just isn't routing to local speakers)