WebCal subscriptions from iPhone are never updated

I’m running the Calendar app on Nextcloud 19.0.2. I’m trying to share an existing calendar on my iPhone w/ the Nextcloud’s Calendar app. In order to do this, I create a new calendar subscription to the url webcal://p11-caldav.icloud.com/...

All seems going smoothly and I can regularly see my calendar events. However, when I update my calendar from my iPhone the mirrored calendar in Nextcloud is never updated. Note: I run cron.php via system cron and it works fine.

How can I fix this?

Solved thanx to this github issue: https://github.com/nextcloud/calendar/issues/1895