Google Tasks not syncing (events do) on the phone I have a OnePlus One running CyanogenMod 12.

I started using tasks within Business Calendar 2 PRO app heavily. They synchronize using google tasks. So I can see my tasks in google calendar. This works well with my Nexus 7 2013 tablet and PC and worked well with the phone too. The phone recently stop synchronizing correctly and does not want to work again. 



Screenshot - Sync (Click to enlarge image)

I noticed that arrows stay present after trying to sync the Calendar. First they wiggle instead of turning awkwardly and end up staying there. The events get synced, the tasks not.

I also have a "Sound Search for Google Play" syncing problem, but I turned that one off for the reason so that it does not interfere. 

I have no idea what to do. Once I had a similar problem with Google Keep and I managed to find a card that was causing some db problem on google site - I removed it and synchronized and it started working again. But I could not see anything interesting in the logs this time.
Following instructions worked for me:

On my HTC M8, I went to Settings → Apps → found the Business Calendar 2 PRO app (it is listed as &quot;Business Calendar&quot;) → cleared  Cache → cleared data of the app (did not need to uninstall/reinstall).

I went back to the Business Calendar app on home screen and it wanted to set up as new but my calendars and most of the data synced very fast (I think it is because I did not uninstall the app).

I had to again choose my tasks' Gmail account and then Tasks were synced correctly!
Also, check your other settings for calendars and others.  I have another Android phone so I use it to confirm that settings match.  The tasks on other phone were syncing fine on Business Calendar.