This problem is observed in all versions of Blender after 2.79
When exporting any model to XNALara, textures are lost (missing.png is everywhere).
The problem is that for some reason the Principled shader (or MMDShaderDev for example) when converted to XPS Shader loses the all textures associated with it.
However, if you manually replace Principled or any other with XPS Shader in each material, the problem disappears.
And to replace it, you must first open any xps model so that the XPS Shader appears in the list, and you can copy and paste it.
This problem is observed in all versions of Blender after 2.79 When exporting any model to XNALara, textures are lost (missing.png is everywhere).
The problem is that for some reason the Principled shader (or MMDShaderDev for example) when converted to XPS Shader loses the all textures associated with it.
However, if you manually replace Principled or any other with XPS Shader in each material, the problem disappears. And to replace it, you must first open any xps model so that the XPS Shader appears in the list, and you can copy and paste it.
Maybe someone can fix this in the code?