Constantly getting logged out of admin interface.

I apologize in advance for posting about what seems to be a common issue. Here are the details.

I created a WP site on a staging domain while it was being developed. Recently, we launched the website by duplicating the database and site files to a new URL with a custom subdomain (ex: http://wordpress.mysite.com)

Since copying the site over, I am constantly getting logged out of the WP admin interface, to the point where it almost happens on every page click. There’s no “session timeout” alert, except if I stay on one page for about 5 minutes.

I’ve double checked in the database and the WP Settings page, and both the WordPress URL and Site URL are matching with the correct domain name. I also checked to make sure the staging site wasn’t accidentally pointing to anything on the live site’s database or domain.

While the hosting provider (Microsoft Azure) is the same for both staging and live sites, their files and databases are separate from each other. I never experienced this problem on the staging site, and I didn’t install any additional plugins after copying the site to the live domain.

I’m pretty much in the dark in trying to find any leads as to why this is happening. Any help is greatly appreciated.