MP4 Files not playing Sound

So I have recently started recording my League of Legends games using a program called Open Broadcaster Software. When I imported to completed recordings into my iPad and iPhone, the videos play, but some have no sound. OBS records and saves files in MP4 with video encoding H.264 and audio AAC. What is unusual is that the recordings all have the same encodings, but some are imported without sound. Any fix to this?

Specifications:

Video encoding: H.264

Audio encoding: AAC

File type: MP4

FPS: 30 Frames

Dimensions: 1092 x 614