I have an Osmo. I have no sound after I upload the file from the sd card to the computer. I do have gain on the indicator in the DJI Go app. I do have sound as I review the video on the iphone. I sent the unit  back to DJI got it back, but with no explination of any repair that was done. I do have gain on the indicator now where I didn't before. Any ideas or solutions? I am using a Rode Video Micro External mic.

I will ask a tech  tomorrow about no sound when playing SD card on desktop and then post.

similar case here

phone playback

Please note these:
1) Make sure you've turn on the Audio Recording in the settings of DJI GO App.
2) Check the audio in Playback and Media Library, please.
3) It may be caused by the incompatibility of your PC

Same weird sound problem here: half of the movies I took last day with the DJI Osmo have no problem. Perfect quality.
For the other half, mostly taken at the end of the day, but not only, I have proper sound recording ONLY when I watch the movie from my DJI iPhone APP with the OSMO on.
Otherwise, either when I upload the files to my computer, or laptop, or macbook, or iPhone through the OSMO app, then, just the video shows up and there is a continuous white noise sound.
So the real sound data is somewhere but the computer or the iPhone plays the white noise sound. I have many codec packs + quick time, VLC and MediaMonkey installed.
It is an interesting but critical software issue as I cannot permit myself to work with the OSMO anymore as if it does record the sound on a random basis.
Please, DJI staff and fan, do something quick!!!