I know this is an old thread, but since this is my first day as a member here, that's my excuse & I'm sticking to it
What I do with DXTBMP without any failures is to load the texture into it, send to the editor, copy & paste your flat painted texture to the the image that DXTBMP provided. In my paint program it's called norm.bmp. This is where the OP may have screwed up now & again, it has to be saved first before sending it back to DXTBMP, if you don't, DXTBMP doesn't "save" the new texture to the flight sim when you import it back from the paint program. The norm.bmp is bur