At one of the hospitals I worked, we were instructed to follow CMS' NCCI Guidelines. If the documentation clearly states bone was removed (29824) and not just debridement (29822/29823) was done, then it would be appropriate to report 29824. Unfortunately, CPT nor CMS does not specify bone size, so a query may be appropriate if the procedure title states "distal claviculectomy" but the description in the body of the op report does not match/support the title. It seems the payer in your situation is following an older AAOS guidelines. A 2017 article by an AAPC member states that as of 2010 the size reference was removed from AAOS publishings.
Hope this helps.