Read the statement by Michael Teeuw here.
UNSOLVED Problem with recuring events
I’ve a problem with the module Calendar: I set it with 3 Google Calendars, and 2 are working… The third contain only recuring events, but I don’t show them… Only simple events are working, could you help me please?
@nico0709 - Have you tried creating a test event in that 3rd calendar that is not repeating? Just to verify that the 3rd calendar is showing up?
Is there anything in the logs when the mirror starts?