When sizeToScene() is called on a Stage that is maximized or set to fullscreen, the whole Window will break.
The OS doesn't matter, every Window manager will be confused, which will result in undefined behaviour.

This behavior is particularly obvious when it comes to Dialogs, as sizeToScene() is called by default there.

It also doesn't matter when sizeToScene() is called, as the request will be saved (when called to early).
In my opinion, a Stage should ignore the request when it is maximized or in fullscreen, as it doesn't make any sense. The behaviour should also be documented.

Might be the same issue as described in https://bugs.openjdk.org/browse/JDK-8316425, but I decided to write a new ticket with more details.