Hi, thanks for the fantastic work!!
I have been using davdroid for quite sometime against my Zimbra installation with no issues. Upon upgrading to 0.9.0.4 (via fdroid), I am no longer able to see any resources after querying at the root level for my contacts and calendars. If I revert to 0.8.4.1 all works as expected.
What version of zimbra do you use?
Can you provide a test accounts or send us logs? Otherwise we cannot reproduce this. Our zimbra test account works fine.