Welcome to the Community. I can help figure out why the payment isn't showing up in the Reconciliation page.
You can check which account you deposit the payment to determine why it's missing when you reconcile.
Here are the steps:
If you choose Undeposited Funds, you may need to make a bank deposit to transfer the payment to the actual account. For more insights, I'm adding the article I recommend on this:
How to Use the Undeposited Funds Account to Receive Payments in QuickBooks Online.
Fill me in if you need any additional assistance from me concerning the payment. I'll be right here to help.