To make sure .OBJ obtained can properly work with SYNCHRO Pro, make sure the .OBJ model created contains the following containing those files / folders:
Sometimes if the .obj is invisible after it is imported to SYNCHRO Pro, it is likely because the texture is set as 'transparent', as defined as parameter:"Tr 1" in the .mtl file. Therefore, replace "Tr 1" on "Tr 0" in a text editor so that all textures NOT transparent, then import the .OBJ again into SYNCHRO Pro.
More information about how transparency is defined in .obj, refer to this article: https://en.wikipedia.org/wiki/Wavefront_.obj_file.