The Projectile Launcher may sometimes identify as the wrong senor or disappear from LabQuest App when it is fired.
Firing the ball takes a lot of power, which can sometimes starve the phogates of the necessary power to function normally. When this happens, the software can miss a measurement, ID the sensor incorrectly (ID as an Angle sensor), or drop connection to the sensor entirely. This is more likely to happen if you fire over and over quickly, or when using an original LabQuest, as it has less power available compared to other interfaces.
A workaround is to use a LabQuest® Power Supply (LQ3-PS) to power the Projectile Launcher.