I currently have two 5400s. I have a GTN650 and when I load a flight plan on the GTN it appears on the main EFIS and I can access it when I select the FPL soft key. However, I am unable to view / access the flight plan on the MFD...the FPL soft key is grayed-out (so is the D -> soft key).

The source is correct (GNAV1) and I can see the leg on the MFD map.