ok, so in the latest version of AE at least, this expression is less than predictable (at least the one from effects and presets, you can create your own using the function in the expression editor)
I’ve attached an ae file link with it working though. — https://we.tl/t-cHRNbfJQsm (1week)
So, take footage, add the sample expression effect. Have your layers in comp with a fill effect. Add a null, make sure the null is at the same point as the layer you want to effect FIRST. attach sample expression position to the null. Then attach null position to your shape layer position(using the expression pick whip not parenting), then pick whip fill to the sample expression colour. should work. Then repeat, duplicating footage layer(can’t have more than one sample layer expression per footage layer I find)
I’m tired and had a beer so I promise nothing but hope this helps!