REAPER Plugin Stereo Audio Outputs (EDIT:Solved)

[color=#BF0000]EDIT: Solved, REAPER also expects the same channel names reported for channel pairs[/color]

Another plugin audio output question for the experts here:

My plugin uses this config:

#define JucePlugin_MaxNumInputChannels 2
#define JucePlugin_MaxNumOutputChannels 16
#define JucePlugin_PreferredChannelConfigurations {2, 16}

and isOutputChannelStereoPair is set to return true. However, REAPER 4, when clicking on the option to build a multi-output config for my plug, wants to create all mono tracks. Any ideas what the problem is?