How did you do the test?
Was the lever in neutral.
If you blow air in an open center valve in neutral, no air will exit the work ports.
If the PB adapter is installed, you should get air out of PB port, and none from the OUT port, or work port.
In neutral, if the PB adapter is not installed and plugged , you will get air out of the OUT port.
If the PB adapter is installed and you shift the lever half, air will exit one of the work ports and the OUT port. If you do a full shift, air will exit the work port only.
A valve that has PB outlet and not used, will have a plug, and the fluid in the galleries will combine and exit the OUT port.