This can happen if you process a credit card without completing and saving the transaction (For example, leaving the page before clicking the 'cash out' button). Envision Cloud will automatically place the ticket On Hold, saving the confirmation code and payment information.
Should you have a Z-Out report that doesn't match the total of your Credit Card Transaction Report, select On Hold Tickets from the Options List on the left side of the Sales Register screen. Check your receipts against the transactions On Hold. You can restore the ticket and complete the cash out process.