I have two itineraries that (one end of March, one in November) booked on CO flight numbers, UA Metal.

When I open the UA itin, I see the same thing (in both of my reservations):

Class: First (NF)

Seating Assignment: (E+ seat assignment)

Upgrade: Pending

Seems like a glitch, can't change your E+ seat assignment though because it opens a first class seatmap (which of course you can't select first class seats).

Is a glitch.