A Solution
If you want to have actors not react to another actor there often needs to be a two way decision to not collide
so you need to specifically say
Destructible (my type is SpecialDestructible)
- I ignore pawns
Character (my type is ECC_Pawn)
- I ignore SpecialDestructibles
If you do BOTH ways it should work!
Go to
ProjectSettings->Collision and add a SpecialDestructible Object type
then check your DefaultEngine config file to see what exact channel it was set to
then in code you can set the object type to be your custom channel
I’ve done this sort of thing many times over and can verify it often does need to be a two way decision to ignore or overlap or block 
ps
#DefaultEngine Config
will look something like this
Profiles=(Name="PhysicsActor",CollisionEnabled=QueryAndPhysics,ObjectTypeName="PhysicsBody",CustomResponses=,HelpMessage="Simulating actors",bCanModify=False)
but you can just use Project Settings->Collision to set it up
you might also find the change in Saved/Config/Windows/Engine.ini