Thanks for your report.
E/davdroid.DavSyncAdapter(16580): Caused by: android.os.TransactionTooLargeException
The number of items in this VCALENDAR is too big for the transaction. Adding every event is wrapped in a transaction (already one transaction per event).
This is a duplicate of #274.
I’ve had a look around for various android calendars and it seems that aCalendar is one of the top rated/recommended ones. So many to choose from…!
I’ve installed it and it works perfectly! Calendar & Task (aCalendar + paid version).
Thanks again for your help.