Quick DP, not sure if this is normal or happened to others, but I did a SDC to a later flight and was able to get it. However, I was not showing up on the waitlist for upgrades and had to call it in. Took the CSR about 5 min to 'transfer' my upgrade request to the new flight. Just throwing that out there - if you do a SDC, double check to make sure you are also on the new upgrade list.