This is not a bug, but an intentional mechanism. 
But I think from a customer's point of it, it can be changed/improved. 

Here's what happens on Windows WorkDrive sync when you relogin it discovers already existing Zoho Directory and asks you three options: 

In all three options it's not true to the word 'sync'. As it's not syncing with my recent file versions of folder structure, rather it recreates the entire directory with fresh download. 

More info Move, Merge, or Rename Sync Folders on Setup (zoho.com) 

Imagine you have hundreds of GBs of data in WorkDrive, being downloaded again for merge or rename! I don't agree with this option given & I propose the Sync app should:

intelligently identify the changes in existing PC folders,

overwrite the modified files,

delete the files that are removed from cloud but are present on PC

and download only new ones and modified ones. 

(just like MS OneDrive does at the time of syncing on Desktop??)

I dont want to download TBs of data and keep the duplicate files. 

What do you think? Should it be changed and this new feature be added?