You can try to clear your browser's cache, @cmklong. 

When you click on the Go to client's QuickBooks drop-down, that'll show you the list of all your clients. Upon selecting the account, that should automatically route you to the client's account.

Check this article for more information: How to access a client's company in QuickBook Online Accountant. 

If it's unable you to move from one client to another, then it's possible that piled-up cache in your regular browser caused this unusual behavior. You can clear your current browser’s cache to resolve this. 

Try using a private browser when switching from one client to another. If it works, proceed and clear the cache in the one that you're currently using.

Here’s how to go incognito or use a private browser:

• For Chrome, press Ctrl + Shift + N.
• For Internet Explorer or Firefox, press Ctrl + Shift + P.
• For Safari, hold down Command + Shift + N.

Here's the clearing temporary internet files and cache article for detailed instructions. 

You can also use other browsers like Chrome, Safari, Edge and the like if the steps above didn’t work.

Let us know if you need further help with your account and or anything else. The Community is always here to assist. Have a wonderful day!