Snoop doesn’t support loans and mortgages right now so you won't be able to see them in the Snoop app, even if you've connected your loan/mortgage provider as you have a current account or credit card with them.
Snoop is mainly focussed on 'Payment Accounts' eg a Current Account or Credit card to help with your spending. You can manually track mortgages, loans etc with Offline Account with Snoop Plus.