Some of my order invoices have a download link

Hi

I have my Appointments+ products set as digital products in marketpress. This is because I dont need to collect people's shipping address so want to make the checkout process as quick as possible

Of about the last 10 orders I've had about 3 of them have contained a "download" link in the invoice order. The rest didn't.

I don't want a download link obviously but is there anything obvious I'm missing to cause this. I've checked the products and they are all set up similar so can't see why some would have a download link and others don't

Kind Regards
Kieran