YouTube App Not Logging-in Due to Blocked Cookies

I have recently downloaded the official YouTube app on my iPhone 6 Plus (Latest iOS 8.3 installed). However, upon attempting to logging into the app with my Google account, I receive the following:

"Oops! Your browser seems to have cookies disabled. Make sure cookies are enabled or try opening a new browser window."

I have tried the following with unfortunately no fix yet:

• Settings > Safari > Block Cookies > Always Allow
• Settings > Safari > Clear History and Website Data
• Settings > Safari > Block Pop-ups (tried On, and tried Off)
• I can successfully log into my Google account in Safari with no problems.
• YouTube app is updated to the latest version.