@Esri: why is the "Use symbol types compatible with all clients" checkbox toggled OFF by default? It took me a while to find it, and now I have to remember to check it every time I publish a map (and have this conversation with everyone else in the office whenever their published map symbols fail). Is there a way to set the default to ON?
For anyone else trying to find it:
When you publish a map with a feature service, you have to click the "Configuration" tab, then click the pencil to edit the configuration settings on the Feature Layer. Then again click the "Configuration" tab, and toggle the checkbox ON for "Use symbol types compatible with all clients". Screenshots below.