You don't really say which side of the split everything is supposed to sit. There's a split point you talk about but it'd be more clear if you gave the range of notes or added "and below" or "and above" so it was clear which side of the split each PART sits.

At any rate - that's not necessary to try to help you here. Be aware that there is more than one place to generate a "split" aka to define a note limit or note range. The most "in your face" note limit is the one which defines which notes sound when played "directly" (not by an ARP). Reference manual page 27 ( https://jp.yamaha.com/files/download/other_assets/9/812529/montage_en_rm_a0.pdf ) for the home screen method of setting or reference manual page 58 for the PART (Common) -> "Part Settings" -> "General" way of setting this same parameter.

There is also a note limit for Arpeggios. Reference manual page 75 (the picture for the screen is on page 73). This is set by PART (Common) -> "Arpeggio" -> "Common" and selecting the "Note Limit" parameter. From the reference manual:

Note Limit (Arpeggio Note Limit)

Determines the lowest and highest notes in the Arpeggio’s note range. Each Arpeggio will only sound for
notes played within its specified range. If you first specify the highest note and then the lowest note, for
example “C5 to C4,” then the note range covers both “C-2 to C4” and “C5 to G8.”

These aren't the only places to set note limits. There are ones for zones, elements, and also different screens where the ARP note limits can be set (the one documented here is fine).

I'm guessing you're setting the wrong note limit for what you want.

Ok,

I have split on the left hand for Piano ARP from C2- C3, on the right hand from C3- G8 I will add the other part for lead solo.
So when I play a chord on the Left hand the Piano will be playing the Piano ARP for me and I do the solo lead on the right hand, but when I play the right hand lead, the Piano ARP is still playing along with my lead voice,

Thanks

Pick your piano (ARP) PART from the home screen. A menu will popup, choose "Edit". Make sure the lower-left blue "Common" button is pressed. Then select the menu (far left-hand column) "Arpeggio" -> "Common" (where Common is the 2nd column from the left). Then look for the "Note Limit" setting. What does that say?

Also - is your ARP changing when you play the right hand solo notes? Or is it staying the same (without change) and the problem is just that it doesn't stop playing? I ask because if you have loop ON and also hold ON - then the ARP will keep playing, like a lot of the drums do, when you lift off the keyboard. I'm assuming this isn't the type of issue you're detailing.