Hi - i know this was a while ago - but i have the same problem - i have just put a message up called:
" Minim lib: AudioRecorder mac osx.5.8 and 6.8 file created in sketch folder but no audio recorded - works on PC Windows 7."
Since i have to work on a mac for my processing project, the fact it works on PC is no good to me.
Did you work out what to do to resolve this problem? If so, i would be v.v. grateful for any tips - i've been trying to sort this out for 3.5 days now so any help would be most deeply appreciated