VIXIA HF R800 Missing audio

[FaithChurch]

We have been using the Vixa HFR800 for a  couple of years and have not had any issues until now. We recently recorded for 2 hours and have a great video but NO sound what so ever. Any advice as to how we can find the sound or why this might have happened would be greatly appreciated. I recorded a short video afterwards and I found that video had audio.  So we had audio prior and afterwards but not during this one video time?? We did not use any external mic, but just tried to pick up sound using camera microphone.

[shadowsports]

Greetings,

If you had on camera audio before and after just one clip, I would try reformatting my SD card and performing a series of tests to see if the behavior happened again.