Contacts won't sync on One Plus Mobile???? Contact Sync Problem on Android Mobiles?? OnePlus contacts app does not sync???

Contacts won't sync on One Plus Mobile????  

Contact Sync Problem on Android Mobiles?? 

OnePlus contacts app does not sync???

OnePlus Contacts app hasn't synchronized since Many Months???

When  try to sync contacts, the loading sync keeps going and never ends??

Tried:
- Downloading contacts app
- Clearing cache and data of the app
- Upgrading system to latest version C.40
- Trying to sync from settings -> accounts

Solution:-

OnePlus Contacts app hasn't synchronized since Many Months???, according to the Google account settings screen. Turning on and off sync has no effect. Restarting the app, clearing the cache also have no effect. There are no error messages that may help to fix this. 

SOLUTION: 

This was finally due to a lack of storage space... 

Once done, everything synched again. I would have appreciated an error message saying this was the reason though.

To Sync Your Gmail Contact on Device Automatically, You Need Minimum 10 GB of Free Space on Your Mobile.

This is Due to a Bug in Oneplus Mobiles. And Still this bug has Not been addressed/solved by Oneplus. 

This is still not resolved from OnePlus but it is such a ridiculous bug. Just to sync contacts of some KBs, we need to keep 10 GB of free storage.

I'm always low on storage and having to free up and waste 10GB of available storage space is just a nightmare but it's the only way my Google Account and its services (Keep, Contacts, Calendar, etc.) continue syncing on my Oneplus.