Iray preview in viewport stopped with latest update

Joltrast

EDIT: Seems to only be affecting one scene with G3F (containing just a single model, no lights or props) and not others, which is even more bonkers!

I updated to the latest version last night (4.9.1.122 - 64bit) and now the viewports will not show preview renders in Iray mode. I don't have an nVidia card (yet) so this is all off the CPU. The CPU sounds like it's trying to preview render, but nothing really happens. If you move the model on the axis with the mouse, you can see a fuzzy, low rez version of the texture, but as soon as you stop moving the camera around it goes back to untextured (grey).

If I could roll back to the previous version I would. I rely on this for lights, DOF cameras etc. I've updated my Intel and AMD drivers, but that didn't help.

Any suggestions I can try? Thanks!

Getting a lot of this in the log file. Don't know if this is good or bad...

(internal: 0.713180s, 1.4fps, overhead 19.3%)2017-09-16 18:13:38.663 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Scene graph creation took 0.080579 seconds2017-09-16 18:13:38.678 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Material update took 0.014470 seconds2017-09-16 18:13:38.678 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Decal update took 0.000001 seconds2017-09-16 18:13:38.678 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Lights update took 0.000002 seconds2017-09-16 18:13:38.818 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Geometry update took 0.138957 seconds2017-09-16 18:13:38.818 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Top group update took 0.000001 seconds2017-09-16 18:13:38.818 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Scene update took 0.154186 seconds2017-09-16 18:13:38.821 Iray INFO - module:category(IRT:RENDER):   1.0   IRT    rend info : Environment update took 0.002753 seconds

 

Padone

I have a Geforce card but I did set iray to use cpu only and it works fine here. Also I checked with the task manager and gpu-z that only the cpu is used. I know this probably doesn't help but it's just to let you know.