Mayfly MicroSD card not recording properly

Hello,

We’ve had a Mayfly station that had the Mayfly board (version 1.1a) replaced in April of 2025. We download the data monthly and the board has been working well up until this spring. When I checked the data for April, the microSD card (8 GB SanDisk Edge) had multiple file extensions I have never seen (see photo from May 6th). The microSD card had a csv with about 5 days worth of data (missing the majority of the month of April). I had run a scan and repaired the card and was checking it once a week in the field and it seemed like everything was fine. However, when I checked the data at the beginning of July, only 3 data points (about 45 minutes of data) had been recorded for the month of June. I thought the microSD card was possibly going, so I tried to swap it out for a new one. I downloaded the data this afternoon and now the second microSD card (also a 8 GB) has similar files I saw back in May.

Has anyone ever had this happen to them? If so, does anyone have a suggestion on how to fix this?

Thank you