Hey Craig,
Open your scene in the “UV Edit”.
Check your UV mesh. Enable the correct UV tag and texture for the editor. Find the finger nail [uv]-polygons. Paint in bright green for example on them. The UVs for them should not have other polygons over them, sometimes if there is no UV for a polygon, then the left upper pixel will fill the area for example. If there is just one large quad polygon, that has the size of the texture… HyperNURBS (Subdivision Surface) and its texture settings(?) or or or…
Without scene file, it is guess work, which I found always a little bit of a time waste—on both sides ;o) I guess you don’t like to “publish” the model, so the support can keep that as well “confidential”.
However, it is all about information flow. It is logical if all parts are know. It feels perhaps chaotically and cryptically if one piece in the information flow is missing. Considering that it works somewhere and somewhere else not at all.
All the best
Sassi