A user in my company reported an issue with her managers shared calendar. Everyone in her department has access to it and are on office 2013 or 2010 her manager is on 2013.

when she attempts to add an entry into her managers calendar she has to invite him this sends her manager an email each time. she is the only user in group on a MAC and as such her manager is asking why she keeps sending invites. If she uses OWA she can add to the calendar without issue. Is there anyway to rectify this or is it an idiosyncrasy with 2011?