If your Preview in Ghost admin does not work...

Once I deployed this blog site, I realized that all Preview from Ghost page, post and design section displayed only blank page.

The reason was because my ghost config url was set to https://jinhyoungkim.com. However, my Nginx configuration has 301 redirect to https://www.jinhyoungkim.com on this url. Therefore, this redirection causes this preview issue.

1. SSH into your host server
2. Go to your ghost blog source code directory
3. Run the following commands  

# Change your ghost config url to right one
ghost config url https://yourcorrectghostdomain.com

# Restart ghost
ghost restart

In my case,  I ran this command:

ghost config url https://www.jinhyoungkim.com

Hope this fix can be useful and resolve your issue! :)