Outlook msync problems

Hi
I am using zoho my company as well as my customers
All of us are using msync for mobile and outlook
We have an annoying problem in synchronization as all inbox and sent items are pretty good on mobiles.
But on outlook some items is not appearing on sent items folder
Also some received items is not appearing in inbox
Although mobile and web are pretty fine

We are using a varaity of outlook versions starting from 2007 till 2016 and all versions are suffering from that issue.
Any body have an idea about how to solve