GHL does not support CAD for bank transfers, it will not allow us to disable credit card payments on invoices.
There is an article about the feature here.
We should be able to disable all payment methods on individual invoices if they do not support CAD direct in GHL.
Better yet just support CAD bank payments.
The inability to disable online payments makes invoicing hard. Generally we cannot send invoices via GHL and we use QBO for this, for anything other than design fees and small services.