mapjfx problems

Since some time now users have reported that mapjfx does not properly display the maps. I wrote a small JavaFX application which is just a WebView and a textfield to edit an URL. This application as well shows buggy behaviour in not loading the map tiles properly. This is the plain JavaFX WebView, with no adddition, custom Javascript code or things that mapjfx does:

Other browsers have no problem with these pages. I do not know if this is some bug in WebView – or more probably in WebKit that’s used internally, but there is nothing I have found up to now that I could do to work around.

This map-tile loading problem only seems to happen with OpenStreetMap servers, I have up to now found no problems when using Bing Maps.

Edit 29.03.2018: At the moment I do not see these issues when running with Oracle JDK 10, feedback about this is very welcome!