Randomize Num FX? (single value)

How can I get the Randomize Num FX to only trigger once?

E.g. I want a trigger to occur and have the result be a single randomized value for the associated slider.

The way it currently functions, it seems to randomize twice before stopping. You can observe this by adding a data source of clock beat 1 or a keypress with a Num FX of Randomize.

It always seems to randomly hit one value then land on a second. I just want it to snap to a single new random value.