Thanks rfc2822, I confirm that changing the range setting to the empty string does work around the issue.
FWIW, as a mere user, I cannot really fix the server side issue. I can report the bug report upstream to the owncloud developers. But the fact remains that there is something very basic (synchronization) that used to work in previous davdroid release, and that no longer works with recent releases — tagged as 1.0 nonetheless.
So while you’re absolutely right in saying it’s owncloud’s problem rather than davdroid’s, you might very well lose users over this. So if there is a way you can by default work around this issue, it might be in the best interest of davdroid users to do so.
With many thanks for this wonderful piece of Free Software that you maintain for all of us.