Erase card, powercycle the ECU (=off then on again), start then stop logging (through SD card menu), browse SD card and you should have one log file.
What's irritating is that you have to manually press the "update" button to get the latest file list. Not sure why, but it probably has to do with the file system used and that there is no real time clock (time stamps = no).
I have one car that really needs logging (drag race only) and he's running 1.1.81 just because it works with that firmware. I tried 1.2.0 a year ago and it didn't work out at all. Not sure what the current functionality is, hopefully better but I have to try on a daily driver type of setup to really get some answers.