From the meeting notes [1]:
MS: Apple is not comfortable working under Khronos IP framework, because of dispute between Apple Legal & Khronos which is private. Can’t talk about the substance of this dispute. Can’t make any statement for Apple to agree to Khronos IP framework. So
1. https://docs.google.com/document/d/1F6ns6I3zs-2JL_dT9hOkX_25...
Weird, but at least it explains why they are causing a problem.
Apparently it goes back to how Apple wanted to evolve OpenCL after releasing it to Khronos.