Join Date:Joined: Aug 2013
With problems like yours, I usually disconnect from internet (wi-Fi), clean my Google account agenda from my PC, make a back-up of my phones agenda to my computer (if needed, a clean-up when I have duplicates, missing phone numbers under contacts, etc) and after a phone cleaning with SDMaid, and a wipe cache/dalvik from recovery.
If it still doesn’t work I make a new Rom installation (wipe factory, etc)
I usually import the agenda from my PC after such a procedure, so google takes all my contacts from phone and upload them to my account.
Maybe you can try and see if it helps.