Ultimate Rewards only books through Priceline, so that's not an option. I spent hours on the phone with Chase, Expedia, Ultimate Rewards. Expedia blames Chase. Chase blames Expedia. Finally, I just cancelled my Sapphire Reserve and ordered a new one. With luck, the new number won't be blocked, which would give me access to booking travel again.
Did not get that this was related using Chase's portal. Good luck.