Cubase 9.0.30 Video no longer works with Duet Display

I’ve been using Duet Display to playback video on my iPad for some time now, and it’s a brilliant setup… I can move the iPad to wherever I want to play an instrument, and the video doesn’t clutter up my desktop displays. It’s always worked perfectly.

But since the 9.0.30 update video playback via Duet is incredibly laggy and stuttery. Anyone got any ideas why? And any idea if it could be fixed?