Dual Monitor - Premiere Pro CC

Hello,

I'm attempting to get the Playback screen in Premiere Pro CC 2017 to play on a second monitor in full screen, from my MacBook Pro .. The second monitor is an Acer KK2HCL, and I'm running an HDMI into it from my Macbook ..

The two are connecting up fine, however the Acer monitor isn't displaying just the Playback screen when selected in Premiere Pro > Preferences > Playback (It's also not appearing as 1920x1080p, and appearing 1 & 2 in the Video Device List)

Any suggestions?

Thanks