I'll help you link your employees to QBO, Neil-hodgson.

Once you add your employees through importing, they should show on the EMPLOYEE tab (Refer to my screenshot below). In your case, let's try to refresh the system by pressing F5 on your keyboard. 

If the employees are still not showing, this is probably a cache issue. To isolate this, let's open QuickBooks Online using an incognito window. From there, check if you're able to view the employees. If you see them, go back to your main browser, then clear the cache. We advise users to clear the cache every now and then. This will prevent the program to behave differently.

On the other hand, using a different web browser fixes issues like this (Google Chrome, Internet Explorer, or Mozilla Firefox).

If ever you encounter any snags or you need more of our help, you can always get back to this thread.