has asked me to re-post his answer here:
"There appears to be a minor bug in how this is supposed to react. Normally if one actor is set ignore a type, they should simply ignore each other. However,I just got it to work by having each Capsule Component set to ignore the other type. For example:
Setting the Collision Presets to Custom then...
Spider is set to be of Object Type Vehicle and ignores Pawn.
Character is set to Object Type Pawn and ignores Vehicle.
I’d advise creating a custom Object Response in Project Settings → Collision → Object Channels, just so you have something that is easily re-usable.
(tested in 4.4)"