Allow me to join the conversation to share my thoughts on this situation.
I agree with the steps provided by @trblenk2 and can confirm it to be correct.
To put it in detail, if you're using a browser to open your QuickBooks Online (QBO) company, try a different browser to see if that helps. We recommend Google Chrome since the system is designed to work with that browser in mind.
If it works but you want to continue with your original browser, you can clear its cache. Check the article provided for the steps required for different browsers.
In case you're using the QBO desktop app, you can clear its cache by resetting the app data.