Hi all,
Not sure if anyone is still having this issue. For me as of today, I still have this issue of missing texture or material after importing OBJ or FBX into ArcGIS Pro. Having tried few rounds, GLB format would work fine for me.
If anyone is still having this issue, can try getting your 3D model in GLB format with its texture applied. Using GLB in ArcGIS Pro will keep its texture.