I retrieved my AM (model 1.2.0, firmware version 1.4.0) after it had been in the field for 2 weeks. It was using rechargeable batteries and a 64 GB SanDisk Extreme SD card.The AM was configured to run for 2 hours 45 mins each day which wouldn't have been long enough to fill the card. The batteries had run out (not entirely surprising) but the SD card was dead - it isn't recognised by any computer, e.g. not listed with diskutil on a Mac.
The 'Use NiMH/LiPO voltage range ...' and 'Enable low-voltage cut-off' settings were both checked.
The SD card had been used previously for about a week without any issues.
Is this likely due to the batteries having run out? I have subsequently run the AM overnight with charged batteries and a new card with no problems.
Thanks Alex, I suppose I was just unlucky!