I am also having the same issue I am able to have my application added into GC key account, but unable to create PA's PR tracker account.Hmmm sorry to hear that. I know that gckey when linking, there are 4 categories in the drop down when adding information in the Application details section, maybe try switching it around.
UCI and Application No, might not work, try family name, and DOB, if you haven't done so, of course