Armed warhead damage transfer issue.
When a warhead that is armed collides with something hard enough it detonates as expected.
However, if the warhead is destroyed by block deformation due to an impact to a nearby block it will not detonate.
Easy enough to replicate, but I have attached a blueprint to show this.
Simply make sure warheads are armed and drop the bomb from high up. Note the tiny impact. No actual explosion.
Remove the armour blocks and drop it so that the actual warheads hit the ground. Note the massive difference.