Another update. UA has changed the plane to a different 757-200 config based on the exit rows going from 20/21 to 21/22 with row 21 not having A or F. It went from a 757-200 version 1 (with 169 seats) to 757-200 version 3 (with 176 seats). The flight is now J1 and Y0 with two blocked up front.
There are no E- seats for choosing and I was not auto-assigned a seat again. EF shows two seats still blocked (same two as previous aircraft - 25BC). I guess if there are no E- seats for assignment before check-in that I will get a "See agent" on my BP?
-RM