recently needed to add 'sound.channel_mask = 3' in order to get in-game sound?

[fitness88]

Using my monitor I lost in-game sound a few days ago and needed to add 'sound.channel_mask = 3' into my E:\saved-games\DCS.openbeta\Config/autoexec.cfg in order to get in-game sound working again?  Interestingly I did not have any such issue using my VR HP Reverb G2.

Anyone know what's going on?

Thank you.