@Taz56 Paid attention this morning on the way to the office. The rear heat button (defrost) does not make any difference as I thought it did when I did a quick test.
So the two little vents don't blow when floor only is selected, had to turn on main vents and did not mess with defrost.
They did blow warm air but the flow is not equal to the main vents so less air coming out.
It seemed like they took longer to blow warm air than main vents but not sure on that one.