Audio Help with DaVinci Resolve 12

Novice editor here asking for some help with a small problem. I'm currently using Nvidia's "instant replay" recording feature to capture game footage. The capture program outputs an mp4 that Resolve will take but when it is put into the timeline there is no audio; more precisely: there seems to be a very short amount of audio at the beginning, but nothing for the rest of the video (when the whole video should have audio). For whatever reason, given my lack of knowledge and experience, I decided to run the video through Handbrake and then, whaddayaknow!, the audio is now being imported as well.

My question is this: does anyone know why the audio is not being imported properly with the original capture? Is there a way to fix that without having to run the video through a quick-fix like I currently am? Here are the file properties for the original capture and the file run through Handbrake. Any help is appreciated and more info can be provided if needed.