Can't see view of map (KDE Neon)

[bigdog]

I've just downloaded RouteConverter and tried to run it under KDE Neon on my Asus UX530 (i7, 8gb). When the application starts I can only see the window, or part of the screen, which has the "Convert" and "Browse" tabs. I can't see the map portion of the display and can't resize the pane/screen to reveal the map. I can see (and resize) the "Elevation" pane. Selecting "View" > "Maximise Map" minimises the "Elevation" pane but leaves the "Convert/Browse" pane filling the screen. 

I've tried changing the size of the application's window and even changing the screen resolution in an attempt to be able to reveal the map, all to no avail. 

This happens both with the current version (2.21) and an older version I tried (2.19, in case it was a problem with the latest version) 

Does anyone have any ideas please? 

Many thanks.

[bigdog]

Solved. 

I installed the default Ubuntu version of java (default-jre). Removing this and using the version from the Oracle PPA has enabled me to resize the panes and see the map.

[routeconverter]

That's because only the Oracle JRE contains JavaFX.