Following your link I found https://github.com/owncloud/calendar/issues/1002 and the second comment has a solution that fixes the problem for me. I did a vimdiff on his file and without understanding much I can tell you that the changes look reasonable. I have only been testing for 5 minutes but so far it works.
CalDav Tasks lists only sync on account creation
Steps to reproduce:
- Have OpenTasks installed before DavDroid as per installation instructions
- Connect to an existing CalDav account.
- On account creation, DavDroid asks which Task Lists should be synchronised.
- Opening OpenTasks correctly show the Lists.
- Now create a List on your CalDav server.
- Going to DavDroid and hitting refresh doesn’t add the new list, nor is there an interface to add the list.
- Allow a “Automatically add new Lists from the CalDav account” when creating accounts and check for new Lists automatically on sync.
Thanks for a great app!!!