It appears that creating a feature service from ArcMap 10.6.1 that has symbology based on Quantities - Graduated Symbols with class ranges of Natural Breaks (Jenks) does not display in the Legend when viewing the web map in Collector. It does appear in the Legend in ArcGIS Online. I also tried to test displaying symbology in the Legend using the Beta app (Aurora/Collector app), but this also proved unsuccessful. Has anyone been able to successfully do this? Thanks.