Hi,
The CIMPolygonSymbol is not rendering it's CIMSolidStroke symbol layers if also using a CIMSolidFill symbol layer with a color set by primitive override. If disabling the primitive override for a CIMSolidFill color and using a fixed color value, the CIMSolidStroke layers are rendered just fine. Also, the symbol is rendered correctly in ArcGIS Pro. Only the JS API is troubled by the problem.
Here is a sample map: https://www.arcgis.com/apps/mapviewer/index.html?webmap=92ed57d2bf34475a8f5e2bb730eeaeaf.
The webmap rendered in ArcGIS Pro:

The webmap rendered in JS API:

Any idea how to solve this?
Thanks,
Matej