In your Sync Status in RECUR360, if you see "Error Code: 3170 Error Message: There was an error when modifying a ReceivePayment. QuickBooks error message: You need to delete this transaction from the deposit before you can edit its name or amount" it means RECUR360 cannot Void the Payment in QuickBooks because you put it on a Deposit in QuickBooks.
To fix the error, in QuickBooks go to the Deposit that Payment is on, click on the line to highlight it, then click the Edit drop down menu in QuickBooks and choose to Delete Line.
Then save the Deposit in QuickBooks and then run the QuickBooks Web Connector again. RECUR360 will then be able to Void the Payment in QuickBooks.