I'm come across a very nasty bug.
Client: openSUSE 13.1 with MONO 3.0.6
Server: openSUSE 13.1 with Owncloud 6 serving files via webDAV (sabreDAV 1.7.6-stable)
How to reproduce:
Open local file, try to sync over URL (https webDAV).
After entering webDAV server credentials and after verification a dialog box pops up (syncing) and at that time the file on the remote end gets deleted and sync fails with server response: error 404 (not found).