IRAY Interactive Rendering: Black Background/Settings Advice

Cowrie

I recently discovered that I can render some scenes in the under the Interactive setting of the Iray engine that would cause Daz to crash when I use the Photorealistic setting.  However, when I went to render a scene that had been giving me trouble in this manner, the background, which should have been an HDRI, rendered solid black.  The figures in the scene looked more-or-less correct in the render, it's just the background that's not showing up.  I've had HDRI backgrounds work fine for other scenes using Iray Interactive rendering, so I have no clue what could be causing this problem.  Anyone know how to fix this?

Another issue I've had with multiple scenes is that in some areas, the shading on a figure can be very abrupt, with there practically being a line between shadowed and fully lit sections when the transition would ideally be much smoother.  I was wondering if there are any settings that can help with this in interactive renders.  It seems like something in the 'Shadows & Lighting' section might be likely to be able to change that, but I'm at a loss to what the settings there actually do, so some advice or explanations regarding that would be nice.

 

EDIT: Further note, while the background goes black in actual renders, the HDRI appears as normal when I'm in the Iray preview mode.  In case that information might help pinpoint the issue.