Wavelab will not assume file properties for a render in place, so this is normal behaviour - internal resolution is 32 bits, so that’s what the new file will be (possibly with 8 or 16 bits at 0). If the render is to a named file, you have to tell WL what properties the resulting file should have. So if you reduce bit depth to, say, 16, you have to define a 16-bit file format.