I recently purchased a used MX49 in great condition. I did a factory reset and restored the original settings. It seems to work well, but there's just one issue with it that I can't figure out. I don't know if it's a setting or an actual problem with the keyboard and would greatly appreciate any insights.

1) I assigned AP 01:Cncrt Grand to Part 1 and ORG 017:RtrVibrato to Part2.
2) I then turned on the "Part Select" button so it is lit up.
3) I have a Roland DP-10 sustain pedal plugged into the Sustain Pedal jack.
4) I select Part 2 (RtrVibrato organ), play a chord with the sustain pedal fully depressed and the modulation wheel turned up slightly for the rotary effect, then back off the rotary (using the modulation wheel) while still sustaining the pedal the whole time.
5) While the organ chord is sustaining, I switch to Part 1 CncrtGrand (pressing button #1), release the sustain pedal and start playing single notes with Part 1 CncrtGrand selected. Unfortunately, the Part 2 RtrVibrato organ chord won't stop sustaining and continues holding, even with me no longer depressing the sustain pedal.
6) The only way I can turn off the sustaining organ is to press the Part 2 RtrVibrato organ (button #2) and tap the sustain pedal. That stops the organ.

I notice this only happens when I have engaged the modulation wheel to turn on the rotary effect while depressing the sustain pedal. If I sustain the organ chord without engaging the modulation wheel, then the organ stops "holding" after I switch to Part 1 (Concert Grand) and release the sustain pedal while playing piano notes. So, there seems to be something about turning on the modulation wheel/organ rotary while depressing the sustain pedal triggers a "hold" on the organ which can only be stopped by reselecting Part 2 organ and tapping the sustain pedal to turn it off.

Is there a controller or other default setting that may be causing this issue? This does not happen on my other Yamaha keyboards (MOX6 and MOXF6) when doing the equivalent (changing Parts while sustaining a rotary organ chord) in Song/Mixing.

Thanks, in advance, for any suggestions/solutions.