Welcome to Android Central! Completely silent, or is there anything that sounds muffled?
Try recording in Safe Mode. Same problem? https://support.t-mobile.com/docs/DOC-25053
Into the headphone jack.Was it the kind of selfie stick that plugs into the headphone jack, or did it connect via Bluetooth? If it plugged in physically, then maybe something about the plug interfered with the mic contact in the jack?
Yes. Other videos were recorded with that selfie stick and there is sound.Have you confirmed audio input via the headphone jack with other video's from that selfie stick?
I ask because a similar issue was discussed on another thread...guy was unsuccessfully trying to transfer songs from one device to another via the headphone jacks. I also noticed the earbuds that came with my phone lack a mic as well....the group more or less decided there was no audio input via the headphone jack.