Cannot Change "Install Location" Under Player Settings for Android Application

Should be simple enough question, I hope.

As the title states, no matter what I do, I cannot change “Build Settings” → “Player Settings” → “Other Settings” → “Configuration” → “Install Location”. It appears to be stuck on “Automatic” when I would like to switch it to “Prefer External”, as I am building a Unity3D VR application for GearVR.

Thanks for any clues!

EDIT - Nevermind - Oculus changed requirement to be “auto” - I’m using an older submission validation tool.

I’m having same exact issue. I’m using Unity 5.5.0p4, building for GearVR. Install location must be “internalOnly” otherwise it fails the Oculus submission checker. I cannot submit builds to Oculus with this issue!