When importing an FBX with several different meshes and multiple materials with "Combine Meshes" enabled the materials will get assigned to incorrect portions of the mesh.
I've included a version of the same asset that will import correctly called "Fixed.zip". The asset that is fixed has had all the meshes attached in the 3d application prior to import. This allows the asset to import as 1 mesh.
Another way to get around the issue is to import the asset without combining meshes and use the "merge actors" tool in the editor to recombine them.
REGRESSION?
Yes
Worked: Launcher Binary 4.13.2 CL 3172292
Broken: Launcher Binary 4.14.3 CL 3249277
RESULT
Certain material slots will get assigned to the incorrect portions of the mesh.
EXPECTED
The asset imports with the same materials assigned to the same portions of the mesh.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-40814 in the post.