Hello,
This is normal since Alsa is using the audio jack output as default audio card. You need to change this default configuration and select the Audio card that is assigned to the HDMI audio. Using Linux, I made it as below:
$ gplay-1.0 test.mp4 --video-sink="kmssink" --audio-sink='alsasink device="hw:3,0"'
Hope this can help you.
Best Regards,
Diego.