I've run into the same issue with the seat maps, not sure why its that way. Possibly because they are still in the process of adding the couple extra seats to the planes still? The Delta app seat maps for the A321s I flew this year didn't show row 26 being there, so I'm pretty sure my seat mates were displeased when they boarded and found non exit row leg space.

I've sat in 27F before and from the looks of 26E, it has a good amount of room. Similar to what 26B and C might have or even more. When I would head over to the bathroom I would actually go through that row instead of row 27 due to the extra space.