Only one video recorded without sound

I use my iPhone XS to record videos very frequently. Recently I recorded a video that had no sound when played back. Every video before and after this one has sound. I even recorded a video less than a minute after the 'no sound' video and it had sound. I exported the video to my iMac and it still has no sound. All the other videos I exported to my iMac have sound. When playing the video back on my iPhone, the speaker icon is not greyed out. I always use the iPhone camera, no third party apps. I had already updated to the newest iOS. Is there a way to recover the sound?