Unexpected offset when using attach tracks with scene root components

We noticed an inconsistency when using attach tracks, depending on whether or not the parent actor has a default scene root. This creates an unintuitive behaviour for animators.

It can be reproduced in 5.7 and 5.8.

Steps to Reproduce

1. Create an actor BP and add a skeletal mesh under its default scene root component
2. Add the BP to seqeuncer
3. Add a cube to sequencer
4. Position the cube in the characters hand
5. Add attach track to cube using one of the "Preserve" position options
6. Observe the cube does not preserve its existing position