Usually after sending an online payment to the FI, it gives you a check number and a jagged lightning icon with payment information. In this case, after sending, I temporarily moved the matching transfer (credit card account) from one account to another and then back again. One wouldn't think that would affect any of the information the FI has to make the payment. When I did that, the payment information is gone and the transaction appears like a non-online payment with no check number. Resending it yields a duplicate error from the FI so I know that the FI has the payment. I admit this is not a common occurrence but it seems to me that Quicken can handle this better. At the very least, it should warn that the payment information is being removed.
Quicken Premier 2013 Release R 12 (22.1.12.7) Windows 7 Ultimate SP1 x64