When working on textures and rendering in MR, MR would not render my textures that I had fixed in Photoshop and reloaded in Maya. The swatch would refresh, but it would continue to render the old image. I found the problem was with setting my project correctly. I never actually set my project (I knew it could be a bad thing, but thought "just this one time..."). Once I did, and put my texture file into that project, it worked correctly. Hope this helps someone out there.