Substane to Iray

Hello Cyril,
Yes, I often use Iray from within Substance
Painter as I find it a superb render engine. but find it is hamstrung
within Painter so I have earlier today subscribed to the Iray for 3 DS Max
plugin. And now have the ability to add lights/ rotate the model
independent of the environment ect just far more flexibility. Have started
using it just now but if I export from painter using the default pbr
exporter when I plug the maps into pbr material slot in 3 ds max they do
not have any effect on the model [ when rendering ] although they show in
the viewport. but when I go to render the model it stays plain white ie no
materials. Could you advise.