can't set default input channel on mono source?

On Nuendo 6.5.4, Mac OS X 10.9.5, right click on an MONO input in VST Connections, there is no option to set it as the default input source,

On Cubase 8.0.1, same computer, there is an option to do that.

Is this normal behavior?

Also, when I make a new audio track, it defaults to an input that is not the one I have set as the default. Is this set somewhere else?

Confused.

Sorry, to clarify: this happens on mono input tracks only. I can right-click stereo input sources in Nuendo and set as default input, but not mono input sources.

Both kinds work in Cubase though.