WWE officials were well aware of the issues Orton was facing about a week ago about not being cleared according to PWInsider. There's some speculation going around that it maybe a concussion related issue, but it has not been confirmed by Orton himself yet despite PWInsider saying it is concussion related.  Orton did pass some of the Impact concussion testing that is needed to get cleared, but he apparently was not passing them consistently enough to where company doctors felt he was good to go. 

PWInsider is a credible source, and WWE officials were aware of the issue, so it is likely true it's not just speculation if WWE knows.