The recent changes I made to the ModelConverterX preview turn out to be a bit buggy. To be honest that’s not a surprise to me. I am still learning the OpenGL shader language and also the fact that every graphics card might handle the shader code slightly different does not make the job easier. But I like the bug hunting and it helps me to learn more about the shaders as well.
So a big thanks to all the users who encounter these problems and report them to me. Your reports really help and I try to iron those bugs out as soon as I can.
And if the bugs really prevent you from doing what you want to do, please revert to the stable version 1.3 for the moment. The development has hardly any new functions, except for those preview changes. So you are only missing the bugs.