Nextcloud Account Sync Problem

I have a Nextcloud account set up on my XA2 that I use for contacts and calendars. Since the last Sailfish update, I have the following problem:

looking at the account settings, all my calendars appear twice. They also show twice in the calendar app.

But both contacts and calendar events don’t upload to Nextcloud anymore. If I add events or contacts in Nextcloud directly, they download to the phone, but new events or contacts added on the phone don’t upload to Nextcloud.

I deleted the account, re-created it, but my calendars show twice.

Any idea how I can fix this?