This is a duplicate of calendars keep being turned on in calendar app (visibility) since update to 1.0x and it’s fixed with 1.0.4. Please follow up there if there are further problems.
Syncing fails without warning on TLS CNAME mismatch
Issue #447 ist still present in 0.8 .
I changed the dns name of my server, without adapting the TLS certificate. The CNAME on the certificate does not match the dns name anymore. davdroid silently failed to sync for a week without me noticing.
I am no expert on the android TLS api, so I cannot tell why the exception is not marked as to be displayed.
Maybe it would be a good idea to display a notification if syncing failed for a prolonged time even if caused by soft errors. If something (dav server, dns, whatever) failed for a long time it would be nice to at least know that something is wrong.
Thanks for your report. I agree and this is not intended behaviour as certificate errors are hard errors which should be shown. Please follow up in #507.