HeretoThere
Just completed lengthy call received from US Consumer Affairs in Winston-Salem about same topic in response to my inquiry.
Wife & I cleared US1 upgrade 7 days out & were assigned 2D & 2F - arrived at RSW day of departure to receive 1A & 2F - no explanation - we luckily changed rows/seats.
I also had same issue about 4 days later LAS/PHL - had 3C assigned in advance - ended up in 1C at check-in - no Sky Marshall on either flight!
Consumer Affairs is investigating my complaint.