Actually, this is not an error. The controllers 50-54 mimic the "button presses" of a MIDI controller.
If the slot is selected, 1 will trigger "Morph Button Down" which starts the morph ramp to go to maximum.
If the slot is not selected, 1 will trigger "Select Slot"
In both cases, a 0 will trigger "Morph Button Up" which means "releasing the button". This starts the morph ramp to go back to minimum if the time between 1 and 0 is more than 300ms or just notes that the next 1/0 pair will trigger the morph ramp down.
This might sound more complicated than it is, just check out the manual regarding the Remote which describes the mechanics in details for the foot switches 1-5.
The idea is to get Remote functionality for slot selection/morphing as easy as possible with a MIDI board.
You can also just use MIDI program changes if you program this from a MIDI track or so.