Problem with NRPN and Pedal Pitch

When i try to load the "pedal pitch" to e.g. stomp box A by using this NRPN message: cc99 50, cc98 0, cc6 0, cc38 50 (Stomp A, Select Type, MSB 0, 50=Pedal Pitch) it loads perfectly. But when i try to change the pitch by using the "heel pitch" parameter on the kemper amp (or with anotoer nrpn message), it shows me that the parameter changes, but it doesnt affect the sound at all. so its showing me that it pitches everything down 12 semitones, but its still the original sound. even though mix is at 100% and the stomp box is On. That only happens when trying to load the pedal pitch via an nrpn message. loading it manually via the kemper amps buttons works fine. am i missing something or is it a known bug with nrpn and the kemper? by the way, all other stomps seem to be working fine when loaded via nrpn.
best,
felix