I have an envelope sustain control that goes from 0 to 255 and then value 256 is HOLD.
I can set a fader to sweep through 0 to 256 no problems.
If I try to add an overlay at value 255, it says HOLD when I go to 255.
If I try to add an overlay at value 256, it says HOLD when I go to 0
Any MIDI value greater than 255 sets the overlay test position to 0