I noticed that since some updates almost a year ago, I am now able to save some advanced symbology settings involving Symbol Property Connection to ArcGIS Online like the one below, at least to some extent. For example, it works with one setting and suddenly the layer stops showing up when I added another Symbol property connection. It is unpredictable what's the capacity of ArcGIS Online to display layers with advanced symbology created in ArcGIS Pro (the desktop app).
At first, I was only able to set color using attribute, but now I noticed that most recent ArcGIS Online is able to render everything I set from color to line width, but loading speed is a little bit problematic.
Is there a documentation that specifically list out advanced Symbology settings that is not yet supported in ArcGIS Online? Does Esri plan to further update ArcGIS Online so that at some point whatever users are able to create in ArcGIS Pro can be displayed properly in ArcGIS Online at reasonable speed?
Are you able to share the Pro project with that symbol defined? You can toss it into a group and invite russell_jsapi and I can take a look. As for the overrides they should work and we can take a look from your sample and see if we can spot an issue regarding rendering and peformance. Thanks!