Hi, I have the same problem: a new appointment created on my T-Mobile Vario II (HTC TyTN) WinMobile 5 (Mr. Brown) device will not appear in iCal, although the sync log says "Add 1 events from Mr. Brown". And if I delete it from the pocket PC, then the sync log says: "Del 1 events from Mr. Brown".
So it looks to me that SyncMate is somehow convinced it's doing the right job, but iCal just doesn't get it.
And this happens always since a few months ago, since I updated from Leopard to Snow Leopard (now it's updated to 10.6.2, but also with 10.6 was the same)
For both Contacts and iCal I use the <-> option, and I only sync a specific group/calendar. But also trying Mr.Brown -> iMac does not help. I also resetted the history from SyncMate, from the preferences of iSync, does not help.
I have on other sync software on my computer. I tryed once MissingSync, but I uninstalled it, I do not remember if using its uninstaller. Could you tell me where to look, to see if there are still leftovers?