How might Colliders be treated differently on retina iPads?

I’ve created an ‘endless runner’ game. Most everything behaves properly except for a couple of collisions, one between the runner (BoxCollider) and some overhead hazards (BoxCollider), and another between the runner and certain coins (SphereCollider). Where it gets tricky is that these missed collisions only occur on very high-res devices like the iPad Air (1536 x 2048), NOT on lower-res ones like the iPad Mini 2, or even in the Unity IDE simulating that same 1536 x 2048 res. There is no logic in the 3D world that alters anything based on the screen size or dpi or anything, and since it only happens on device (and inconsistently, at that), my debugging options are a little more limited. The frame rate is fine, so it’s not missing them for that reason. So I pose this unfortunately broad question:
How might SphereCollider and CubeCollider be treated differently on retina iPads?

Most common is framerate being different on different devices. Usually the slower frame rate will miss “thin” collisions, since it mores more per frame.

In theory, the hirez devices could have lower FPS. Say you have a complex scene to draw, lots of overalapping transparent objects, particles. Doing all the math for 100% more pixels on a CPU only 75% faster. But that’s only a guess, fitting the “slower framerate” guess.

The framerate was easily sufficient, but your reply is appreciated.
I ended up solving this today, though in a way that left some details unanswered. The object used in both of the described collisions had a disabled mesh renderer component and a box collider component. The box collider was larger than the mesh’s bounding box, so I reduced the collider to fit the mesh’s bounding box, and then scaled them uniformly together to match the old size. It worked, so it seems like the collider was being shrunk down to the size of mesh’s bounding box when it exceeded it, though I had written no functionality that would do this sort of thing. Kinda nonsensical, but it is demonstrably fixed…