Encountered this for first time last night. Had the exit single seat on an erj145 and noticed I had been banished to the back of the plane. The exit seat was still open so selected it. Checked the res again, and I was in the back again, but this time the exit seat was occupied. Checked it this morning and I was back in the exit seat.

Edit: just did olci and enjoyed three festivus miracles. The seat assignments stayed. The web site said I was wait listed for CPU. I got an actual BP for my international trip.