Shared folder on Linux guest doesn't allow enabling symlinks

[dragon951]

Host: Win7 64bit 32GB memory
Guest: Ubuntu 16.04LTS 64bit 16GB memory
Vbox: Version 5.2.0 r118431 (Qt5.6.2)
GuestAdditions: Same issue with VBoxGuestAdditions_5.2.1-118447.iso and VBoxGuestAdditions_5.2.1-118918.iso
Guest Name: Benderbrau
Shared Folder: Linux

Tried to enable symlink support via powershell command: (in C:\Program Files\Oracle\VirtualBox)

.\VBoxManage.exe setextradata Benderbrau VBoxInternal2/SharedFoldersEnableSymlinksCreate/Linux 1

Restarted VM and host, but get a 'Protocol error' when copying symlinks to shared drive (other files successfully copy). Tried running Virtualbox as administrator to no effect. Attached the VBoxHardening.log in case it is useful.