Default plane collider doesnt work properly when stretched?

In my game you have the ability to shoot projectiles (capsule), these projectiles are supposed to explode when they collide with an object, however when shooting towards the ceiling (Plane) the projectile sometimes doesn't explode. Up on further inspection I noticed that a certain face (triangle within the plane) of the plane does not trigger the explosion (I'm using OnTriggerEnter and have tried OnTriggerStay without any difference) but other faces do I also tried making the ray ignore the plane but that resulted in the projectile simply moving through it. so I decided to make a new plane to experiment with it. when the scale was x:z = 1:1 everything seemed to work fine but when i scaled it up to 100:100 around 30% of the projectiles didnt explode and 70% did. has anybody got an idea why this happens and how to fix this? I could probably just use a Cube with a box collider, but I was just curious why this happens and if it is possible to fix it.