Hi, @lpclawn. Thanks for posting your concern here.
I see that you're unable to add a bank deposit in QuickBooks Online. Don't worry, I have some troubleshooting steps to share with you.
Before that, may I know if you received any error messages? Any additional information will help me provide the most suitable solution to your query.
In the meantime, I'd suggest opening your QBO account in a private window or incognito. The system occasionally behaves strangely when the browser frequently accesses pages. It could be due to corrupted cache files in your browser.
You can use these shortcut keys to access a private window or an incognito:
Mozilla Firefox or Microsoft Edge: CTRL + Shift + P
Google Chrome: CTRL + Shift + N
Safari: Command + Shift + N
Once done, try adding a bank deposit again. If it works, return to your regular browser, and let's clear the cache to have a clean slate in your QuickBooks account.
Otherwise, use other supported web engines to learn what computer and browser are needed for the best experience when using QuickBooks.