Welcome to the QuickBooks Community. I can see the importance of being able to View Register in QuickBooks and I'll be happy to share more info so you're on the right path.
It's good that you've cleared cache and cookies as that's one of the methods for troubleshooting this issue. The other method is checking to make sure you're logged in as the Admin user on the account. Some users on the account may have access to certain capabilities that other users can't access. You can view the register by Clicking on Chart of Accounts > locate the account in question > View register. If this option still isn't showing, I suggest contacting our phone support team so they can help dig deeper into this.
Schedule a Callback or start a Chat: click (?)Help in the upper right in QuickBooks Online > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.