I have a brand new Mac with 16GB ram running OS 10.10.5 and Audacity 2.1.1. I had an unsaved project that totally crashed. I rebooted per the instruction on the FAQ, but the auto recover couldn’t recover. The track was 37 minutes long and a podcast interview for school.
Where do we say that you should reboot? A controlled reboot (as opposed to the Mac crashing) will lead Mac to empty the Audacity temp folder, I’m afraid. We do have a bug report open to move the Audacity temp folder to somewhere that survives reboot.