EQ Curves have gone from Channel Settings and Mixer view

At some point in working with a range of projects in the last 2 days - EQ curves have stopped displaying in the Channel Settings and Mixer views.

Channel settings view shows a blank black square where the eq curve display should be. Mixer simply shows no curves at all.

Eq is functioning and can be edited with knobs.

Safe start to default factory settings does not correct the issue.

Running Cubase 8 Pro on Windows 8.1 64 Bit.

Best Regards,