Is Sync button works fine if LVT crossed in SharePoint Online for Document Library ?

Hi, 

I have SharePoint Document library having more that 10k files. 

Is Sync button for offline usage on machine visible for more than 5k records ? Also, If yes I am not able to see this button for the library. And, another user is able to see button but its not working.

Regards,

Pratik Darak