Office 365 calendar syncs some events, but not all of them

I have a user who is having some events not sync from her desktop Outlook to her iphone calendar.  We have her set up on the phone (as with all users) as an Exchange account.  Her mail works fine, but she does not get some events coming over to her calendar on her phone.  They just will not sync.

I thought that something might have gotten hung up, so I deleted the Exchange account on the phone, then went into the Exchange properties on the Admin portal of office 365, went into her mailbox exchange properties and deleted the link to the iphone in the mailbox features > ActiveSync details box.  After making sure the link was deleted, I recreated her account on the phone and everything came back, just as expected, BUT she still says some things still aren't syncing over.  Any help is greatly appreciated!