How can I confirm what actors are colliding with a UVehicleWheel instance?

I have a C++ pawn class that uses the USimpleWheeledVehicleMovementComponent class for its movement. I am trying to test how it will work when driving across surfaces with different physics materials. I am having trouble with the wheel colliding with an actor I cannot identify.

Using the UVehicleWheel:: GetContactSurfaceMaterial() I can see I am colliding with two different objects at the same time: one with the default material and one with a test material I made. I can’t see any actor that has the default material that may be colliding with the wheel. I have confirmed the pawn skeletal mesh and wheel static mesh are not colliding (checked by changing their material, the collision was still the default material). I have also checked the wheel static meshes OverlappingActors array, it is empty.

How can I confirm what actors are colliding with a UVehicleWheel instance?