As the title says, my issue is that videos I upload do not play audio on mobile devices but work fine on desktop. I've confirmed this with other users as well, so this is not just a problem with my phone. I've also tried using both the m.you.com page and the YouTube app. I'm on an iOS device and I've also been told it's the same on Android devices.
Here are a couple of examples:
I use Adobe Premiere to edit and use one of the YouTube defaults to render to. Specifically "YouTube HD 1080p 29.97" which is a H.264 format. The file type is .mp4.
Any help as to why this happens would be greatly appreciated.