org -> caldav does not sync

[mkasu]

I can't get org-caldav to run correctly. When executing org-caldav-sync, it correctly syncs entries from my remote caldav server to org-mode. However, for the other direction, org-mode to caldav, nothing happens.

For example:

========== Started sync.
Check connection for https://caldav.messagingengine.com/dav/calendars/user/MY_USER_NAME/MY_CALENDAR_NAME/.
Generating ICS file /var/folders/mh/4lv_h_q920q3hjt9wzlrfnkh0000gn/T/org-caldav-6623EqH.
=== Updating EventDB from Org
=== Updating EventDB from Cal
Cal UID 3333322c-1445-431d-afd1-dbb9a6768cb1: New
=== Updating events in calendar
=== Updating events in Org
Getting event UID 3333322c-1445-431d-afd1-dbb9a6768cb1.
Event UID 3333322c-1445-431d-afd1-dbb9a6768cb1: New in Cal --> Org inbox.

It correctly syncs my 1 remote test entry, but no org-mode entries. However, when I look up the ICS file in /var/folders/.../org-caldav-6623EqH, it has hundreds of entries. For some reason, org-caldav does not seem to detect them correctly and skips the "Updating EventDB from Org" step completely.

Any suggestions?

My config:

(setq org-caldav-url "https://caldav.messagingengine.com/dav/calendars/user/MY_USER_NAME")
(setq org-caldav-calendar-id "MY_CALENDAR_NAME")
(setq org-caldav-inbox "~/Dropbox/org/caldav.org")
(setq org-caldav-files (quote ("~/Dropbox/org"))
(setq org-icalendar-timezone "Europe/Berlin")
(setq org-icalendar-use-deadline '(event-if-todo event-if-not-todo todo-due))

[mkasu]

Short edit: It seems I was mistaken and the .ics is not always filled with data.

Directly after org-caldav-sync, it is empty, which explains why nothing happens. When I subsequently call org-icalendar-combine-agenda, then the previous tmp file (same name as in org-caldav-debug-log) gets created with content.

How can I successfully generate it during org-caldav-sync?