pCustom Expression Produces Different Result M1 vs WIN

I only have a very rudimentary understanding of expressions and this one was not written by me but this behavior is quite odd. The expression is part of a somewhat larger set but I have stripped it down to the basics. It behaves as expected on Windows but not on a M1 Mac and I cant fathom why. In a simple text-pImageEmitter-pCustom-pRender com with the particles tab position coordinates set as,

px if(time==1,rands(-10,10,id*50),px)
py if(time==1,rands(-10,10,id*150),py)
pz if(time==1,rands(-10,10,id*250),pz)

On my windows machine behaves as expected. On the first frame particles are distributed randomly all over the canvas. Same composition, same expressions on the mac bunches the particles up way down in the lower left corner. Seems like its only executing the pz portion.

Noticed this a long time ago but today made sure to update to 18.6.5 on both machines and try again. Same result in Fusion Studio.

Regards

{
Tools = ordered() {
pImageEmitter1 = pImageEmitter {
ID = 2,
Inputs = {
XDensity = Input { Value = 0.1, },
YDensity = Input { Value = 0.1, },
AlphaThreshold = Input { Value = 0.068, },
LockParticleColorToInitialFrame = Input { Value = 1, },
Lifespan = Input { Value = 1000, },
Input = Input {
SourceOp = "Text1",
Source = "Output",
},
Style = Input { Value = FuID { "ParticleStyleBlob" }, },
["ParticleStyle.ColorControls"] = Input { Value = 1, },
["ParticleStyle.ColorVariance"] = Input { Value = 1, },
["ParticleStyle.RedHigh"] = Input { Value = 0.597, },
["ParticleStyle.BlueLow"] = Input { Value = -0.169, },
["ParticleStyle.BlueHigh"] = Input { Value = 0.091, },
["ParticleStyle.SizeControls"] = Input { Value = 1, },
["ParticleStyle.Size"] = Input { Value = 0.05, },
["ParticleStyle.SizeVariance"] = Input { Value = 0.005, },
["ParticleStyle.SizeOverLife"] = Input {
SourceOp = "pImageEmitter1SizeoverLife",
Source = "Value",
},
["ParticleStyle.BlurOverLife"] = Input {
SourceOp = "pImageEmitter1BluroverLife2D",
Source = "Value",
},
},
ViewInfo = OperatorInfo { Pos = { 202.771, 250.43 } },
},
pImageEmitter1SizeoverLife = LUTBezier {
KeyColorSplines = {
[0] = {
[0] = { 0.5, RH = { 0.333333333333333, 0.5 }, Flags = { Linear = true } },
[1] = { 0.5, LH = { 0.666666666666667, 0.5 }, Flags = { Linear = true } }
}
},
SplineColor = { Red = 192, Green = 128, Blue = 64 },
},
pImageEmitter1BluroverLife2D = LUTBezier {
KeyColorSplines = {
[0] = {
[0] = { 0.5, RH = { 0.333333333333333, 0.5 }, Flags = { Linear = true } },
[1] = { 0.5, LH = { 0.666666666666667, 0.5 }, Flags = { Linear = true } }
}
},
SplineColor = { Red = 192, Green = 128, Blue = 64 },
CtrlWZoom = false,
},
Text1 = TextPlus {
Inputs = {
Width = Input { Value = 1920, },
Height = Input { Value = 1080, },
["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
StyledText = Input { Value = "GALAXY", },
Font = Input { Value = "Open Sans", },
Style = Input { Value = "Bold", },
Size = Input { Value = 0.2564, },
VerticalJustificationNew = Input { Value = 3, },
HorizontalJustificationNew = Input { Value = 3, },
},
ViewInfo = OperatorInfo { Pos = { 210, 210.854 } },
},
pCustom3 = pCustom {
ID = 43,
Inputs = {
PositionXExpression = Input { Value = "if(time==1,rands(-10,10,id*50),px)", },
PositionYExpression = Input { Value = "if(time==1,rands(-10,10,id*150),py)", },
PositionZExpression = Input { Value = "if(time==1,rands(-10,10,id*250),pz)", },
Input = Input {
SourceOp = "pImageEmitter1",
Source = "Output",
},
},
ViewInfo = OperatorInfo { Pos = { 204.112, 292.6 } },
},
pRender3 = pRender {
CtrlWZoom = false,
Inputs = {
_MotionBlurWarning = Input { Disabled = true, },
Width = Input { Value = 1920, },
Height = Input { Value = 1080, },
["Gamut.SLogVersion"] = Input { Value = FuID { "SLog2" }, },
["MaterialID.MaterialID"] = Input { Value = 5, },
["ObjectID.ObjectID"] = Input { Value = 4, },
Input = Input {
SourceOp = "pCustom3",
Source = "Output",
},
},
ViewInfo = OperatorInfo { Pos = { 201.918, 331.169 } },
}
}
}