Canon ran into some audio-issues with their latest firmware update but were super quick to fix this issue :-)

There was a phenomenon in which the manual recording settings made in C1/C2/C3 were changed and sound could not be recorded if manual sound recording was used in the C1/C2/C3 settings and the camera was subsequently turned off (or if Auto Power Off was activated). This does not occur in modes other than C1/C2/C3.

Get the new firmware update here >> EOS 5D Mark II Firmware Update Version 2.0.4.

 

Cheers!

   Daniel