Thomas, you misunderstand, when you switch it to toggle, that's what that means, you have to actuate the sustain pedal again for the keylab 88 to output a 000 message, ie, toggle switch.
I suggest that as a makeshift solution because at least then the keylab 88 behaves consistently.
Judging by the responses here, it looks like Gate mode won't work until a firmware update is released for the keylab 88.