Is there any chance audio can be recovered from a video recording which appears in QuickTime and other apps to have no audio track?

Running macOS 10.12 with a security app called EvoCam that records ".mov" MP4 files. It records in one hour segments using the built-in iSight camera and microphone. In one hour long segment the audio cut out. And then in the subsequent videos, there is no audio at all. When I open them in QuickTime, it does not mention there being an audio track. I also tried opening them in VLC with no luck. I am not sure what happened as there was no error message and the microphone is working. Quitting the app and restarting it caused it to start recording audio again. Is there any chance the audio is in the file but corrupted and might be salvageable? I have found some services that do video repair and I even opened the video file in one such service's app. It's an app called Treasured. However, that service's app didn't say it found audio, just H264 video. This is an older Mac set up for security purposes, and the audio is very important if it can be recovered--would be willing to pay for a service or app that could recover it, but I'm not even sure if it's possible that it's there. This did happen once before and the same thing (quitting and reopening the app) worked, but the audio wasn't important in that instance.