I guess you know the issue that OpenChange does not yet update the folders automatically so you have to use SHIFT+F9 to Update All Folders - we are desperately waiting for this embarrassment to be resolved (our clients cannot believe it ...) - if you have done this and it is not resolved, try removing the OST file and sync again - if there was a pre-existing OST file Outlook may fail to access the file and therefore cannot populate it.