Trying to publish a feature layer with a very basic symbology; no fill, just a basic hatch to match the outline color. Adding the layer to a new web map in AGOL keeps the outline color but changes the hatch color to black. I have other polygons that used the same symbology conventions and their hatch colors were all changed to black, too. Is there a way around this, so that the hatch color and outline color match, like they do in ArcMap before publishing? I've tried publishing to Portal and out of Pro with the same results.]2
ArcGIS Online uses the ESRI JS API 3.26 and can use the symbology that's available through the API. Here is a link to the different symbology you can use. You can change the renderer of the hosted feature layer by updating the definition. I haven't tried everything in the sandbox but so far everything works out. This doesn't solve the problem of limited symbology but it gives a bit more freedom.