Hi Chris, and welcome to planDisney!
Hmmm, this is a tough question, but I think I may know your hiccup.
Disneyland Resort tickets use a tier system, with each ticket going from tier 1 (which has the most number of blackout days) to Tier 6 (which has the least number of blackout days). The tier system allows Guests to pay a lower price for days with less demand, making the tier system a way for families and Disney-lovers to save money.
The next few months through the summertime are historically restricted to higher-tiered tickets. It's possible that your ticket is blacked-out through August 29th, and that is why you are unable to book a new reservation. You can check the blackout dates for one-day tickets on the
Disneyland Resort Website. If the cause of your issue is due to blackout dates, you may
speak to a Cast Member about upgrading your ticket or wait until a time when your ticket is available for use.
And whenever you are able to make it to the Happiest Place on Earth, I hope you have a chance to take a photo in front of Cinderella Castle at the end of Main Street, U.S.A. Whether with a
Disney PhotoPass photographer or as a selfie, taking a photo is such an easy way to capture the moment and let the memory live forever.
Best wishes,
Lola