I want to help ensure that this Payment link issue is taken care of now.
Processing payments is an add-on feature offered by QuickBooks Payments. Customers won't be able to pay directly from your invoices if you don't have QuickBooks Payments, but you may still email them.
You must enable the feature to let clients pay straight from an invoice if you have QuickBooks Payments.
Here's how:
Click the gear icon ⚙.
Choose Account and settings.
Select Sales.
Under Invoice payments, click Edit ✎, then select the payment options you want.