Why would the "Learn" function not work for me when assigning VST quick controls

Cubase
1

I am unable to assign custom Quick Controls or parameters in Remote Control Editor.
First I was trying this in Kontakt, with Sacconi Strings. It has no pre-defined parameters, so I was trying to use the “Learn” button to assign some of the parameters in Remote Control Editor. It wasn’t working. I thought, oh, might just be Kontakt or Sacconi Strings.

So, I tested it out in UVI Falcon. Again, no luck. I tried the “Learn” in Remote Control Editor again, and later tried to just do the Quick Controls, but I couldn’t have those learn anything either.

Then I tested bx_oberhausen — a VST which has pre-determined quick controls with pre-defined parameters. But when I tried to change any of these pre-determined controls, nothing happened. I tried the learn in both the QC and RCE, and then also tried to just pick a different control from the dropdown in the RCE . I also tried Remove All Assignments, to start from scratch — but still no luck.

What am I doing wrong?

Nuendo 14
Mac OS 13.6.5

2

I have been playing around more. The quick controls as expected in audio plugins — I tested in ValhallaVintageVerb and Softube Drawmer S73. Worked as expected in both.

I was really hoping this wasn’t a bug.
Is anybody else having this issue? Or can find a flaw in what I’m doing?