If you're finding an Offline Payment isn't sync'd with QuickBooks Online, first check to see if you have the Sync enabled for that payment.

First, from the Billing Tab click the three dots next to the Offline Payment and click 'Edit'.

Next, check to see if the 'Disable Sync' box is checked.

If so, un-check it to allow the payment to sync and click 'Save Payment Record'.

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