This flow sensor has no specific in and out so that can not be the problem. When you set the connector to flow within the aquasuite: did you shutdown the PC to perform a restart? This is necessary because otherwise the pump will not use the new settings.

If everything is OK so far, you should test the mechanic of the sensor itself. Blow some air into the chamber and check if the impeller is spinning easily. If it spins hardly or even not at all you can open up the the sensor. Remove the stainless steel cover. Underneath you will find a white plastic cover, remove this too. Now you can access the impeller. Don't remove it and check if it spins easily without the top cover. If so, remove the impeller, get a hammer and hit the metal pin two or three times. Maybe you ask why: it is very likely that the metal pin sticks not deep enough into the drilled hole so the impeller touches the top and can not spin freely.

If there seems no problem with the pin, just check the chamber and impeller for dirt and other things that might block the thing from spinning.

If you own a multimeter you can also check the connection cable. Maybe this is causing the problem because of a broken wire.