I have the same issue here: Logging on SD card error
Some things that I noticed:
- After every boot, there is a new sessxxx folder, with a 0 byte log file, just as @Jimmy_Hynes mentioned. These files are dated to be created on 1st January 2000. The correct log files and folders are dated correctly.
- When logging and sd_bench is not working, I went to fs/microsd folder in the nsh shell, and tried to list its content with ls, but it showed nothing. (So the new folders and files are just visible on the computer. Also, mkdir failed, but I think it is basically the same problem as the original error.)