Isn't there a Midi Preset "Master Keyboard"? This sends "Lower" out on one midi channel (1?) and "Upper" on the next (2)

The problem with the PSR 3k / 2.1k /2k series (and others?) is that there isn't a single midi channel output covering the
entire keyboard under all circumstances.

The "lower" and "upper" items are always present - if you use "Left", "Right1" and "Right2" they only work when those selections rae active.

You may have to set the module to function using "Omni" midi channel (i.e. respond to all events on all midi channels) in order to get something logical happenning.