I have gcc installed on my mac, and have compiled the stock firmware, and have found AudioMoth-Firmware-Basic, and am now about to try my hand at C programming -- very rusty! This functionality is so important for the AudioMoth to realize its potential, I thought I would post before perhaps bugging for help, and in case there are technical concerns -- and to express surprise that nobody has published on GitHub a mod of AudioMothFirmware-Basic with this functionality. Not that I've found anyway. Wouldn't that be a good thing? Wink, nudge.

Are you using a Mac for formatting cards? I was getting no recordings for some cards. The red and green LEDs would blink once at the proper recording time, then the green LED would resume blinking, waiting for the next recording time. A card formatting problem was discovered: https://www.openacousticdevices.info/support/sd-card-support/formatting-on-mac If not on Mac, maybe there is a utility or similar way to get more formatting details for your cards to check this.