Vertical Scrollabar disappears

I have purchased one of the angular 4 template from themeforest. Angular 4 is setup and demo is running fine.

The issue and difficulties we are facing :
Scrollbar disappears when we move to other page.

Steps to produce this issue :
Go to any page. Scrollbar appears in left side navigation menu.
Now I move to any other page and scrollbar in left side navigation menu disappears.

The theme I have purchased is

Hi @sanjayhere,

Welcome to the forums! You should get in touch with theme author, please go to purchased item page and use either “Support” or “Comments” section: