@rfc2822
No OpenTask, only contacts sync. Android 4.0.4 stock with removed Google Services. Calendar/Contacts not removed.
What is privacy guard?
Please explain which debug info you need? Debug log from app on pastebin in first post.
Probably catlog will helpful?
https://www.dropbox.com/s/8vst7t6qj9e0io4/2016-09-11-23-04-57.txt?dl=0
Maybe provide test account?