What do you mean "a problem"? That there is no card to downgrade to?
Yes. Had the same problem. They said can only downgrade to other co-branded cards (Delta etc) which all had AFs.
Dan recommended HUCACACA. Tried 6 times. Finally on the sixth time the woman kindly 'assisted' me in downgrading to a Blue cash.
Throughout the process I confirmed with her multiple times that I did not want to apply - only downgrade - and I did not want any hard pull on my credit, which she confirmed.
After all is said and done, I get a call from New Accounts Dept. saying that they just received my new application and a hard pull was done....
I was able to get the pull expunged but just had to close the card (and transfer the credit line).