Symbol layer drawing seems to have no impact if your stroke is a gradient stroke. Please add support for gradient strokes into symbol layer drawing. In the below example, I am trying to get my parcels to appear as blocks with a subtle shadow without having to merge into a whole new layer.
Symbol settings:
Symbol layer drawing, with stroke moved below fill:
Stroke still appears on top of fill.
Solid stroke appears as expected:
Seems related? Symbol layer drawing not behaving - lower layers a... - Esri Community