When I apply Iray MDLs to object surfaces, the standard viewport doesn't seem to update with the new Iray material. Only the Iray preview window and the final Iray render will show those materials.

Is that by design or is it a bug that will be addressed? It's a bit frustrating to not have the main viewport updated, since the Iray preview window takes many seconds to refresh even for just 100 iterations for a smaller image (and I have a GTX 1080 Ti).