If you have a RenderZone license, maybe you don't have it active... check on the menu Help/Register.../Registration/Extensions tab.
As a workaround... for OGL real-time in Shaded Full images, I do screenshots on my Mac mini with a 4K display to obtain 5120 × 2880 pixels if you hide all the palettes and expand to full screen, which is not bad for presentations purposes.
Actually, I don't do CPU renderings anymore for my work... last time was about ten years ago?!
I hope it helps.