B4J Question java.lang.RuntimeException: not supported (Release only)

[Pendrush]

I have modified a bit ServerExampleNoMySQL, everything working fine in debug mode (multi devices get connected and communicate with each other), but in Release I get this error when device try to connect on WebSocket. I'm using B4J v3.7 Beta 1.

java.lang.RuntimeException: not supported
at anywheresoftware.b4j.objects.FxBA.cleanMessageLoop(FxBA.java:37)
at anywheresoftware.b4j.object.WebSocketModule$Adapter$ThreadHandler.run(WebSocketModule.java:186)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

EDIT: OK, I have found similar error on forum, It's a server UI app and that is no go. Converted in non-UI app and everything working as expected.