I was DUMB lol I thought I had changed to JDK 8 but actually didn't. Now I try using JDK 8 and everything works fine. So for JDK 9 after changing to above settings the icon is finally correctly picked ...

This issue occurs for both the jfxcentral and JavaFX Ensemble. When opening the app, the icon appears on the Ubuntu dock while the update progress dialog is showing, but when the app actually loads, ...