Figured it out with help from another forum. For anyone having the same issue here’s the solution:
Make sure your different mesh files don’t internally use the same material names. My issue was that my materials within each file were “noname.001, noname.002” etc… So when Unreal tried importing the materials, it registered that they already existed, and thus never parsed for new textures or created unique materials. So just go in and rename your materials within each mesh file to be unique to that specific file, like “meshname.material.001”.