[wrxtasy]

It was working fine before! What changed is how the Shield enforces and polls HDCP status. It used to be that HDCP was enforced only when the content required DRM. That changed with update 3.1 and now HDCP is enforced as soon as you see the Android logo during boot. It doesn't look like nVIDIA will change this and so, this refresh rate switching issue will remain for ever.

Yes HDCP is enforced on boot with Android Marshmallow. I see this on other Marshmallow HDCP 2.2 capable 4K DRM platforms. That OS release also brought with it 4K HDCP 2.2 protected online streaming.

There was a workaround that could be done on a Rooted AML platform to allow refresh switching and 1080p HDCP 1.x Netflix, but someone would have to get their hands dirty with nVIDIA to investigate that platform.

I would download the DRM Info App and run it to see what HDCP Status is actually being reported by those Shields that are having issues.