There are two possible problems…

If you are importing textures into mudbox:

Make sure you’re files are named properly. This is important because mudbox expects a certain file name structure for textures. For example if your object has 2 uv tiles with the head region being in u0, v1, and the body being in u1, v1 then your file names should be: diffuse_u0_v1.tif and diffuse_u1_v1.tif

You must have the _u0_v1 structure for the tiles to import properly. The word “diffuse” can be replaced with anything for example: duck_face_color_map_u0_v1.tif.  Just be sure to have the _u0_v1 structure at the end of the filename, and change the U and V number values. The underscores are important. They need to be there. Even if you have spaces in your file names. For example: “duck face color map_u0_v1.tif”

If you’re file names are proper, but still not visible in mudbox… The problem might be that mudbox may have unloaded certain texture regions to save ram. This behavior is common for versions before 2012 SAP. If you see any bright blue areas on your model, place the mouse pointer over that area and press the up arrow to load it into memory.

When you export to photoshop it exports all of the uv tiles. It saves them in the folder you specify.