Expected: The result of a 0 interp speed would return the "current" value. This value is currently hard coded to return the "target" when set to 0 or below. This can feel non-intuitive
Result: The return value is set to return the "target" value when the interp speed is set to 0 or less
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-44291 in the post.