No audio in ivms4200 playback, but audio is fine in HIK connect app (android)

[Pot-Island]

I've been unable to get ivms4200 to play back audio consistently, even though playback audio sounds fine on the HIK connect app. I seem to recall that there was a sequence of menus to click through before ivms4200 would unleash my audio, but I can't remember now. Has anyone solved this riddle?

I use a 2CD2347g1-LU camera and a DS-7616NI-I2_16P NVR, both installed about a year ago.