I am curious if these glitches have anything to do with something that I came across yesterday when booking a JFK-SFO itinerary on the 757 aircraft equipped with D1 flat bed seating, the 75S I believe? After purchasing an Economy fare, seat selection shows seats DEF in row 20 and EF in row 21 as Main Cabin (preferred, dark blue) , not C+ (light blue). Is this correct, that these seats are not C+?

What am I missing here?