Fire TV Cube 2nd gen (7.6.8.8) Developer Tools Menu?

I'm looking for the real-time display or system xray stats overlay that I've used in the past. Google tells me I can get there by holding select and down arrow for 3 to 5 seconds and then quickly hit the menu button to display the Developer Tools menu. This is not working for me. I have enabled developer mode, yet no combination of the remote presses wor, for me.

Is this now disabled? Is there an app I can download to display an overlay of real-time video and audio stats?

Thanks for the read.