Sound splitting is bleeding effects

When I split an organ and a bass guitar sound on my Key 61, the vibrato from the organ is bleeding into the bass. In other words, I put a bass guitar sound in the lower register, an organ in the right hand upper register. When I play bass alone the tone is normal but when I play organ with the bass together the vibrato, tone wheel or Leslie effect bleeds into the bass and makes it sound off. When I stop using the organ the bass goes back to normal I'm trying to figure out what this is and how I can correct it. It's been also doing the same thing with EP sounds that have a vibrato effect.

When I attach a midi controller to the Key 61 and split the input on tracks 1 (bass on the midi) and 2(organ on the mpc) instead of splitting the sounds on the mpc alone the issue dissapears

The issue came back again... despite connecting an external midi keyboard to the MPC. I ended up turning off all the midi perform filters for the bass and that solved the problem. The midi filters are accessible from the track view under the Mute and Solo buttons on the right. This workaround is stopping the bleeding effects but now I can't use any filters on the bass....

The CC1 messages (Mod Wheel) were probably being sent to both instruments (the bass and the organ) at the same time.

The Detailed setup with the effects bleeding are...
1. Track 1 Organ soul jazz
2. Track 2 Fabric XL electric bass Round Wound

Tracks 1+2 Armed in the Sounds - Key Ranges screen with the bass split from middle c down and the organ split from middle c up
Monitors set to "IN" on both tracks 1 and 2

Input set to All ports

The solution Akai tech help gave was turning the Modulation wheel down, which does help. The best solution I came up with that worked the best was to turn down the ModWheel, then shut off cc1 Modulation cc129-Channel Pressure and cc128 Pitchbend in the Track Midi Perform Settings of the Bass track