Hello there, @usermeesoon-han. I'll make sure to help you isolate the issue that will help you sync Melio payments to your QuickBooks Online (QBO).
You can perform basic browser troubleshooting. It will help you isolate the issue and make your browser load faster. Cookies and caches might block you from syncing Melio payments to your QBO account.
Restart your browser.
Log in to your account and try to log in to your QBO account and check if the Melio payments are sync in an incognito or private browser. You can use these keyboard shortcuts to launch a new private window:
Google Chrome: press Ctrl + Shift + N
Mozilla Firefox: press Ctrl + Shift + P
Safari: press Command + Shift + N
If it works on the private browser, you can go back to the regular browser and clear your browser's cache. From there, try to log in to your QBO account and check if Melio payments are sync.