Display issues in QuickBooks Online are usually caused by piled-up cache. Cache helps your browser's background processes run smoothly. However, it can also cause unexpected results when piled up. Here are the troubleshooting steps that we can do to get rid of any cache-related issues.
Open a private browser and log in to your QBO account. It uses but doesn't store cache.
If the customer details and invoices are displayed successfully, we can go back to your regular browser and clear the cache.