Please help, 343! Custom map transfer

(This is my second time posting this) I have 60+ Halo 4 custom maps on the original game I have been trying to transfer to MCC on Xbox one. The frustrating thing is apparently there was a one time shared files transfer quite a bit ago that I didn’t know about. A few of my old maps made it onto MCC that were already in file share from my 360, so I know it should be possible. Is there anything I can do here ? I’ve just spent too much time over the years making all these maps to give up on the transfer.

Please keep to your existing topic, thanks