Scene Kit Objects -Z.Position Faulting

Hello, I have had some issues within SceneKit in where I add my assets to the SceneKit editor, once the image is in place I always set the z.position to (-1) / behind the player... Sometimes on running the simulation I notice that occasionally the player either goes under or over the image assets I’ve added.. I’ve changed to either -10 / -50 etc assuming this will place the images back further in the scene. Still getting the same result at random. Maybe a silly question but I thought I’d ask as I must be doing something wrong, has anyone come across this before? :/ Thanks in advance, AJ

Scene Kit Objects -Z.Position Faulting
 
 
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