I am having the same problem that I have seen others report several times in this community. Specifically, I am trying to reestablish the online connection for one of my credit cards (AMEX) that was lost for some reason. After I connect to AMEX and authorize my account, Quicken asks if I want to add a new account or link to an existing account. The existing account that I want to link to does not show up in the list of accounts that Quicken offers. Instead, Quicken offers only checking and savings accounts to link to. (see screenshot)
As I said, I have seen this problem posted many times, but I have not seen a solution that works for me. Any ideas?