My Matek F405 board is not saving logs

I have a Matek F405 board installed in a small fixed-wing model. It has flown successfully for a few flights but it usually doesn’t save a log of the flight. MP simply reports ‘No log files found’ when I connect and try to download.

Attached is the param file. Do you see anything there that might cause it not to record, please? I’m aware there’s limited memory available for log files as there’s no SD card slot on this board, so could it be deleting the file once it exceeds the available space?

Model B after magfit.param (18.9 KB)

I’m still confused! I’ve removed the FC and ancillaries from the model to check it out on the workbench, and today it created a log file while connected to MP via USB and a flight battery even though LOG_DISARMED is set at zero and the FC was not armed (log shows PreArm: GPS 1: Bad fix).

The log is named 01-01-1970 00-00-01.bin whereas on the few occasions previously the logs were named by the correct date and time. I understand the naming thing is something to do with the way the log is store in memory rather than on an SD card, but why is it recording logs sometimes and not others? I delete all logs after downloading them, to ensure that memory should not be a problem.

Here is the log file in question, in case it reveals the problem. The param file is still as in my initial post.