If your RPT file shows error “Warning: special LOD contains 2nd UV set.” then you can try to fix it by using O2 to do the following:

Go to: Surfaces → UV sets

Normally there should only be one UV set in that list (above Add/Delete Active etc…). It should only contain “v Active 0”.

In this case you will have a second one or even more. You just need to click on the UVset that you don't need (clicking on it will set it active) and then “Delete active”.