You probably need to refresh your QBO to get it working again, KPittz.
The cache stores temporary internet files from your browsing history to help your browser quickly load the pages. However, too many files may affect the browsing performance and may require you to clear it out.
The first troubleshooting step we can try is to restart your QBO. If you still don't see your client's data, you can proceed to the second step which is to open QBO using a private browser.
If step two works, go back to your previous browser and clear the cache. Once done, log in to your client's account again and check to see if all the areas in QBO are working.
Please keep me updated with the results. I'll be right here if you need anything else.