Can you tell us which reports aren't working? I'd also like to know if you're getting an error when running reports in QuickBooks Online.
You can also try switching to a different browser and log in to QuickBooks. Then, run a report to check if its already working. Browser issues can cause interruptions when running reports or working in QuickBooks Online.
The program works well with any of these browsers:
Alternatively, you can also switch to an incognito/private browsing and log back in to QuickBooks. Press CTRL + Shift + N for Chrome and CTRL + Shift + P for Mozilla.
Please add a reply below if you want to add more details and if you have follow-up questions. I'll get back here to offer more help.