Usually, the stars who are injured in time for WrestleMania make appearances during the WWE Axxess and Dean Ambrose who is out with an injury was scheduled for the same.
However, the company recently announced that Ambrose has been pulled from his announced appearance and Sting and Ric Flair would be stepping in to fill his place:
Unfortunately, Dean Ambrose will not be able to appear at the WrestleMania Axxess Premium VIP Autograph Session on Sunday, April 8, at 10 a.m. However, we are pleased to inform the WWE Universe that WWE Hall of Famers Sting and Ric Flair will appear at this Premium VIP Autograph Session. Your existing Dean Ambrose Premium VIP ticket will still grant you access to the Premium VIP Autograph Session on Sunday, April 8, at 10 a.m. with Sting and Flair. “
No word yet on the reason behind it but it was reported a couple of weeks ago that the former WWE Champion was in Birmingham, Alabama to have his condition evaluated.
After the announcement, there are rumors of him possibly returning sooner than expected, but the stronger belief is that there may be some complications with his recovery and Officials might have pulled him from this and several other appearances to give him rest.
Dean Ambrose suffered a triceps injury and underwent a surgery back in December. At the time it was reported by WWE that he would be out of action for almost 9 months.