If the option is already turned off and still not getting the shortcuts thumbnail, try the next method. Now relaunch the Chrome by completely closing the program from the toolbar hidden icons.
By turning off, it will enable the shortcut thumbnails in the startup page. We can get back the thumbnail feature using the following methods.
If you are not experiencing the most visited sites thumbnails feature on Google Chrome, here we have a detailed guide to get back them. Whenever we launch Chrome it shows the most visited sites as thumbnails to easily open them with a single click.