DavDroid doesn’t handle exceptions from weekly recurring appointment correct. The exceptions don’t appear on the mobile phone, but they appear in owncloud, which I use as caldav server. I can provide you with an example ics file, if needed.
Algernon83 suggestion fixed it for me. You have no idea how aggravating this was, wondering what the issue was and no time to troubleshoot. HAHA, reinstalled davdroid and rebooted OC server and was about to try some more severe stuff. Thanks.