[RM5.1] 'Choose Button by Mode' action showing unexpected info []

In RM5.1, while introducing a "Choose Button by Mode" action, I notice an "error" of sorts, in the form of nullnul showing in this screenshot:

First time using this particular feature of RM – I'm not 100% sure of its intended purpose? – but took pains to follow prompts and fill all fields. It left me with two questions, as well:

  1. Where does one choose the Device(s) that these button actions are intended for?
  2. Why is "Push" the only choice offered in the Button Action drop-downs?

@gopher.ny I don't know if this is related to the "fix" introduced with f/w 2.3.2 perhaps? or whether this Action is somehow not intended to stand-alone as implemented here.

Another datum... the "Push Button per Mode" action for some reason displays "Choose Button per Mode" at the top, as shown here:

but also shows nullnul directly below.

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