Dawm! You are right!
I have created several height levels for the floor. In one of them the ceiling display was active. I have already spent 3.5 hours with the search. Thank you so much!

Hello,

i currently have massive problems with rendering textures in a project. As soon as I try to render a project with a render level 3 or 4 (BEST) the texture of the ground disappears. It almost looks like an empty white texture layer is always inserted automatically. At level 1 to 2 everything ...

I tested the JAR file under Linux and Windows successfully. Maybe there are some side effects with the Java version.

Regarding a plugin: Just from looking into the source code I don't think that it is possible to implement it as a plugin.

How can I use your Version?
I can't find a final setup ...