Meshroom - why are textures white?

[John Callaghan]

Textures are mainly white, with some correct bits. What am I doing wrong?

Hello there. I know I must be making a very simple mistake but I can't find a solution for my particular issue. I have tried several times, taking clear, evenly-lit images of my source models. I've used green-screen backgrounds (but not in this example).
Although some results work better than others, here's a typical example. The model itself is very successful and has the correct detail, but the textures are mainly white.

I'm a beginner at all of this, and as I say I've tried different variations and have looked around for a solution. I'd appreciate some pointers - thank you!

I've attached one of 500+ source images, the result seen in Blender, how Meshroom looks when it's finished processing, and a JPEG version of what the .exr file looks like.

Any help gratefully received!