Enable grayscale display and you don't get a cropbox, because the image it's zoomed.
In 5x it's not displayed...
I didn't try it yet on HDMI.
Yes, it works fine when in greyscale preview as you mentioned, it's just that I always work in Canon preview. The issues with hdmi also only happen when in Canon preview. I didn't really expect you would work on HDMI issues at this point. Not a biggie.
A few additional notes regarding HDMI for future reference...
- Greyscale preview is not transmitted via hdmi.. so it acts essentially like Canon preview.
- Raw playback does not work via HDMI... locks up the camera.
- Raw Zebras not working correctly
- Raw histogram ETTR hint not accurate