Sending from SES delegate sender always tells me the configuration set does not exist

I have two accounts that have both have been removed from the SES sandbox. In one account, I have a verified domain identity with a default configuration set. I have set up an authorization policy on that identity to allow the delegate account to send. If I try to send an email from the delegate without specifying a configuration set, it selects the default configuration set but fails telling me that it doesn't exist. If it doesn't exist, how did it know to select it? If I create a test configuration set and select it when sending, I get the same message that it can't be found. I've read the docs many times, but no idea where to go from here.