SOLVED - Bug report: Importing ical RRULE with exception

Importing the ical file below in JEvents version 2.1.12, gives strange results. Moreover the frontend and backend imports behave slightly differently. The ical file consists of a recurring event followed by an exception to the recurrence pattern.

Frontend: Nothing gets imported into the calendar.
Backend: The recurring event gets imported into the calendar, but the exception does not.

Changing the order of the recurring event and the exception does yield the expected result (recurring event with simple exception at 2007/12/24) for both frontend and backend import.

BEGIN:VCALENDAR

PRODID:-//http://Mozilla.org/NONSGML Mozilla Calendar V1.1//EN

VERSION:2.0

METHOD:PUBLISH

BEGIN:VTIMEZONE

TZID:Europe/Amsterdam

X-LIC-LOCATION:Europe/Amsterdam

BEGINAYLIGHT

TZOFFSETFROM:+0100

TZOFFSETTO:+0200

TZNAME:CEST

DTSTART:19700329T020000

RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3

ENDAYLIGHT

BEGIN:STANDARD

TZOFFSETFROM:+0200

TZOFFSETTO:+0100

TZNAME:CET

DTSTART:19701025T030000

RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10

END:STANDARD

END:VTIMEZONE

BEGIN:VEVENT

CREATED:20070901T091003Z

LAST-MODIFIED:20120302T112410Z

DTSTAMP:20120302T112410Z

UID:bd047bee-c3f5-4f3d-aaad-0fc774c8332d

SUMMARY:Some Description 1

RRULE:FREQ=WEEKLY;INTERVAL=1;BYDAY=MO,TU,TH

DTSTART;TZID=Europe/Amsterdam:20070917T150000

DTEND;TZID=Europe/Amsterdam:20070917T180000

X-MOZ-GENERATION:104

END:VEVENT

BEGIN:VEVENT

CREATED:20071106T085512Z

LAST-MODIFIED:20120302T112410Z

DTSTAMP:20120302T112410Z

UID:bd047bee-c3f5-4f3d-aaad-0fc774c8332d

SUMMARY:Some Description 2

RECURRENCE-ID;TZID=Europe/Amsterdam:20071224T150000

DTSTART;TZID=Europe/Amsterdam:20071224T074500

DTEND;TZID=Europe/Amsterdam:20071224T180000

END:VEVENT

END:VCALENDAR