Analogue Input alongside RGB Keypad (Circuit Python)

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Hi

I am trying to read analogue input on the Pi Pico (using GP26 Board.A0) monitoring a RobotDyn 4x4 Analogue Keypad (different resistance per button). This has 3 pins: GND, VCC (connected to 3.3v) and OUTPUT which i connect to GP26 Board.A0

If I do this on just a pi pico, unconnected to the Pimoroni RGB Keypad - it works fine.

When the pi pico is plugged into the Pimoroni RGB Keypad I get loads of random values. (See the check() function in the code below)

So far I am hypothesizing that maybe the various things going on in the RGB Keypad is some how either

a) making the analogue pin “float”
or
b) is not delivering a constant 3.3v causing fluctuations (could it be that the 3.3v output pin varies because the current draw of all the leds is making the voltage fluctuate?)

Here is the class for the analogue keypad

class AnKeyPad:
    def __init__(self, midi, nId, pin, callback=None):
        self.midi = midi
        self.nId = nId
        self.prevVoltage = 0
        self.pin=pin
        self.analogue = AnalogIn(pin)
        self.callback = callback
        self.currVoltage=0.0
        self.notches = [29,33,40,49,54,57,59,62,69,74,78,83,97,106,115,126]
        self.notchMap=[0,4,8,12,1,5,9,13,2,6,10,14,3,7,11,15]
        self.midiNoteStart = 36
        self.velocity=100
        self.lastPressed = time.monotonic()
        
    def get_voltage(self, voltage):
        return int((voltage * 127) / 65536)
    
    def check(self):
        global noteBasher
        now = time.monotonic()
        currVoltage = self.get_voltage(self.analogue.value)
        if currVoltage<25:  #basically a note-off type event - when user stops pressing
            self.prevVoltage=currVoltage
            return    
        
        if  abs(self.prevVoltage-currVoltage)>3 and  now-self.lastPressed >.2:
            print(currVoltage)
            nearestIdx = min(range(len(self.notches)), key=lambda i: abs(self.notches[i]-currVoltage))            
            self.prevVoltage=currVoltage 
            noteBasher.noteOn(self.midiNoteStart+self.notchMap[nearestIdx])
            self.lastPressed = time.monotonic()
            if self.callback!=None:
                self.callback(self.nId, currVoltage-4)

Anyone have any ideas what might be going wrong - or just any suggestions of things to check

Thanks

Steve