I just migrated models with materials to another project and after that Unreal Editor tells that it cant find the file location so in doesnt show the material.
If you’re only getting grey squares, and it says can’t find file location then you’re probably going to have to set those materials back up. I’m not sure what your set up is though.
Also what you can do is go back to the other project -> highlight all of your textures/images and the material itself -> right click -> Asset actions ->“Bulk export” and then place it in the contents of the project folder you want it in.
Again I don’t know your set up so definitely take all of this with a grain of salt. It just sounds like when you migrated the material it wasn’t done right so as of right now there’s no material on your model.