Question - Code Physics Collision with a Child Object

[GargantulaKon]

I had to create a custom fixture and then attach it to an instance because I am manipulating the image Y scale and then want the fixture to match the new sprite dimensions. I have an object with a parent in order to enable collisions between different objects. I then have another object that has a custom fixture as a sensor that is set to be kinematic. I then manipulate the Y position with phy_position_y. I set an event on it to monitor a collision with the parent of the child objects. The code doesn't get triggered if I use a custom fixture, but if I simply use the "Uses Physics" checkbox, then the collision check works. Why is that? Am I missing a flag that I need to enable on the fixture before binding it? I tried using collision groups with no luck so far. I tried using physics_test_overlap, but it starts running the code as fast as it can instead of just once per collision. There are so many collision methods for non-physics-enabled objects, but only one for physics. Why is that? How can I program for more advanced collisions?

I was looking at this post for reference: https://forum.yoyogames.com/index.php?threads/collision-bounding-box-doesnt-scale-with-image.23941/