It doesn’t work on 4.7 and also 4.26 
It worked initially but after restarting the game the zombie still try to extend his head
BUT there is no issues with the trees anymore in 4.7
I tried to change the Nvidia installation by Game Ready to Studio, it does nothing
I have this on the Log when I hit the head :
LogScript: Warning: Script Msg: Attempted modulo 0 - returning 0.
LogViewport: Display: Viewport MouseLockMode Changed, DoNotLock → LockOnCapture
LogViewport: Display: Viewport MouseCaptureMode Changed, CaptureDuringMouseDown → CapturePermanently
LogSkinnedMeshComp: execBoneIsChildOf: BoneName ‘None’ not found in SkeletalMesh ‘SK_ZombieAA’