RNBO param @displayname label not visible in Max External or rnbo~ enclosing patcher

Built a RNBO patch that uses params for key attributes. The params all use @enum, @displayname and @displayorder (as in [param noteoff_all @enum Channel Omni @displayname "Note Off Destination" @displayorder 14]).

If I build the RNBO patch into a plugin, the parameters appear properly in the DAW with the labels as defined by @displayname ("Note Off Destination"). This is good.

However, if I build the RNBO patch into a Max External, the displayname/label does not appear in the external object's inspector nor in the attrui, only the name ("noteoff_all").

This is also the case for the Max patcher that encloses my [rnbo~] object: it does not display the displayname/label in the rnbo~ object inspector or in the attrui. In the inspector, the parameter names appear in italics and say "No reference description available".

Am I missing something obvious? Why are the label/displaynames only visible in the plugin build but not in Max Externals or in the enclosing Max patcher?