So I looked into collision and there was something wrong with it. Importing even simple shapes from blender seems to result in very odd hitbox behaviour.
In all instances Falloff Type is set to “None”, so in theory the entire field should be at generating a stress of 9,999,999,999. The max damage threshold of the Geometry Collections is 500,000 so it should be eviscerated.
I first removed the hitbox and then changed Collision Complexity to “Use Simple As Complex”. This had some positive results.
It looks like the issue is resolved in basic testing, as applying a complex hitbox results in the collection ( far left cylinder) being destroyed:
However I was mislead, the new hitbox only makes the collection slightly more susceptible to damage.
Placing the field deep inside the collection works across all cases:
I’m not sure how to split a hull, which I believe is your next suggestion when it comes to troubleshooting.
I’m also becoming really suspicious of the falloff which seems to be applied even when it is set to 0 or None.
For reference, this is the hitbox:
This image is taken post-impulse, so as you can see it is unaffected when the locus of the sphere is not deep inside the cylinder:
Note: once I convert the actor to a Geometry Collection there are no lines to show collision.