I had recently difficulties to re-add severals caldav sync I have. At the end, I could do it but with some workarounds (it is from my memory so maybe not very detailled):
- i have one caldav per calendar (it used to work differently in the past but i could not have it working anymore with several calendars with one sync)
- my main calendar I use mfe
- for the other calendars i am entering the complete address of the google calendar I found in the website: something like:
44gfd5454gds54545g4f@group.calendar.google.com