Problem
If we try rendering a track with only mono media via master with the checkbox "Tracks with only mono media to mono file" checked, the resulting file will be stereo.
To get around this, we can use the channel dropdown in the render-dialog to force it to mono.
However, this is not realistic when you have hundreds of regions and some of them should be mono, others stereo - which is often the case for a game audio sound effect project.
Request
I think the best solution would be to add an option to force to mono on the "Master mix" region render matrix checkbox.
Alternatively, a preference could be added that would allow the "Tracks with only mono media" checkbox to override the master track channel count.