Whenever I try to modify a calendar event created automatically by a pro planning application in my Gmail calendar, I face the same issue: the timezone isn't recognized by OneCalendar (it displays "unknown" in the timezone field when Google Agenda, for instance, displays "GMT+2").
The bug is that when I try to save my modifications to the calendar entry, I get an "unknown timezone" error popup, and when dismissing the error popup, the event modification screen closes but without saving my modifications. :-(
I think that a better error handling would be to return to the event modification screen after