i find the setting
Send invoice when total = 0 | Options to choose from are No and YES (default!)
very counter intuitive.
The highlight text is this:
<strong>Send invoice when total = 0</strong><br />Set to Yes, if no invoice should be sent if the total of an order is 0. Set to No, if an invoice should be sent all the time
Have a good day
forgot to attach
You are right, indeed.