Make sure the portal is somewhere wher eyou can get to it. Like under 'Has Portal' you'll see y, x, z and yaw. (Probably not in that order.) So just place an object where you want the portal, then type in the numbers the object has in the portal destination boxes. Then remove the object if you don't want it. c:
If that doesn't help, then re-install your game. That's all I can really think of. But make sure that you did the one above. And save the maps and objects you have into antoehr file before you delete Feral Heart so you don't have to download or re-make them again.
Hope this helped!