QT3D Quick entity SkyboxEntity does not work in my environment

[Gash]

When I try to use SkyboxEntity background become black and there is statement arrive in console "QTextureImage only supports local url" - but I point to local texture set (6 textures with skybox).
When I change texture path to wrong one - other error arrived: "Failed to open ":/assets/cubemaps/miramar/miramar1_negy.webp" (6 times for all textures) - so I thing that if path to textures ok - then textures loaded and error in some other place.
There are skybox example provided with installation of QT placed in ~/Qt5.12.1/5.12.1/Src/qt3d/tests/manual/skybox.
Basically it uses SkyboxEntity and dont work also.
But there is interesting Skybox.qml included in the project - it defines Skybox entity.
When I change main.qml to use this Skybox (instead of SkyboxEntity) from the project (before it it was unused) then it was no any errors and statements in console but behavior is just the same: black background.

I already waste some time to let SkyboxEntity work but no result yet.
The next step i see - to implement Skybox cpp - it rather time consuming task.
Does anybody use SkyboxEntity?
What may be wrong in my case?

Its easy to reproduce test: just open project <path to QT installation>Src/qt3d/tests/manual/skybox/skybox.pro and run it.