No longer able to previsualize HDRI

Uthgard

Just as the title says: some time ago, just by using Iray preview mode I could see the HDRI, but nowadays I just get a grey background until I render (there are no problems there). I don't know if I have fudged things up while tinkering or if some update changed the way things work, but I have tried following the available instructions to no avail, any suggestions?