This is what I'm trying to render
Codec: MPEG AAC Audio(mp4a)
Sample rate: 48000Hz
I'm trying to create a Left, Right, Center, LFE, Left Rear and Right Rear file to run on a Windows machine, and doing it on a Mac!
It appears that I should use the Apple Audio Toolkit which should allow me to create an .m4a format file which I believe will satisfy the requirement.
When I select this for output and render, it says my destination folder is not available or full. I can render other formats, and have no problem to the same location (about 2T available)
I get the same problem with the AAC format when I attempt to render using it.
I've just downladed Audition CC, so it should be the most current software.
Assuming that Audition is sending the toolbox within core audio what it needs, this sounds like an Apple problem, not an Audition one. But, because it's on a Mac and the vast majority of us don't use them, I can't tell you absolutely. So, you will almost certainly need a developer comment about this.