Let's access your QuickBooks Online (QBO) account via a private or incognito window to check if this a cache related issue. Stored data for a long period can cause unusual behavior to the browser that can affect your QBO performance.
You may use these keyboard shortcuts in opening a private or incognito window:
Google Chrome: Ctrl + Shift + N
Internet Explorer & Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Option + P
Once done, try to post a payment for multiple invoices to double-check. If you're able to post a payment, then we'll need to clear your regular browser cache. This will delete all data stored and your browser can start fresh.
If the issue persists, try using a different browser to check if this is a browser-related issue.
Also, I encourage checking our Income and expenses page to learn some best practices on managing your expenses.
Should you have other concerns or questions in the future, you can always get back to us. We're always here to help. Have a great day and stay healthy.