When attaching an object to the camera of a character in VR, there is a lag when the camera is moving.
In the gif attached, you can see what happens when moving the HMD with a static mesh(cube) attached to the camera by drag&drop in the blueprint editor.
There was a recent bug fix about camera lag which can be related: UE-31787 Vive: Positional Latency w/ Rotation
I am currently using 4.12.5, which includes this fix.
How to reproduce:
Create a new project
Create a new character blueprint
Add a camera to the capsule
Add a static mesh close to the camera (becomes really visible below 60cm)