When using IBl, then preview render with cpu flips HDR image upside down, gpu preview render works correctly.
When in preview render, many operations result in error, which can be fixed with restarting the interactive render. They seem to be operations related to rendering, such as moving objects, changing color space, enabling aov's.
nvidia gtx 965m
For once I can't reproduce this bug on macOS
Not in v1.7.239 anyway.
I've attached a test scene.
The HDRI image renders identically on CPU only or on GPU only and indeed with both enabled for Preview and Production Renders.
The restarting of the interactive renderer for all of those operations though... that's the same on macOS. And stopping the interactive renderer is the main cause of crashes on macOS for unknown and seemingly random reasons. You must press SAVE before stopping an interactive renderer on macOS or you risk loosing your work.
edit: packed the blend file so the image is now included