Exchange 2010 meeting room calendar sync issue

Hi People,

The ladies at the reception are having issues with Outlook 2010 meeting room calendars, they are out of syncing. Sometimes appointment are visible for the other, some times they are not showing up or they do when adding a new appointment. For example: If we look at one day with 5 room calendars near each other all looks the same except 1 meeting is not shown.

Can someone advice where to check sync settings or something like that? 

I created the room mailboxes the regular way with default room settings, just granted them access so they can read/write.

Running a Windows Server 2008 R2 SP1 x64 with exchange 2010 v. 14.2.247.5

Thanks in advance.