If you have invoices that were paid and they show in Pencil but they do not show in Cin7/DEAR, the usual cause for this type of issue is that the Cin7/DEAR integration is the Cin7 API has timed out.
To resolve this, to repush the payment to Cin7/DEAR, follow these steps: https://support.pencilpay.com/knowledge/what-to-do-if-payment-was-made-on-sale-order-and-was-removed-in-cin7
If this doesn't work, you can check if your Cin7 is connected by following these steps: https://support.pencilpay.com/knowledge/how-to-connect-your-dear-account-with-pencil. You may need to disconnect Cin7/DEAR first by toggling OFF the green switch in the top right and then reconnecting Cin7/DEAR.