I’m importing a model from Blender… and when I go to create the capsules for the physics collisions… it refuses to reduce the radius of the capsule beyond 0.5 unless I manually go into the Body setting and adjust it by hand 
why does UE5 refuse to reduce it beyond that point???
I know it has to be from my end… but why does the capsule return to an arbitrary default of 0.5 whenever I resize the gizmo in any direction?
the grid snap settings
set them to one
Are you saying literally 0.5, or are you saying 50 units which is 0.5 meters?
Unreal really wants your units to be centimeters, and your up vector to be Z and your forward vector to be X. Trying to use it any other way, will just lead to lots of frustration and lost hair.