This afternoon we found and fixed a serious problem related to "detached" events (instances of recurring events that have been edited to no longer match the original recurrence rule). Some time fairly recently, Google fixed a longstanding bug that we had coded around 18 months ago, and their fix broke our workaround.
The problem manifested itself this way: if you had a detached event in iCal and synced it, it would get garbled, and partial duplicates would be created. (Specifically, the detached event wouldn't be created but another recurring event starting the day of the detached event would be. It wasn't pretty.)
Since this was a server-side issue, all client versions including the beta were affected. The fix is on the live servers, so the problem shouldn't happen again. However, if you have had recurring events corrupted by this bug please do this:
- Delete the corrupted events from iCal and Google
- Recreate the events in iCal OR Google (doesn't matter which)