Max 2020, Corona v5
Open the attached scene, open Slate.
In the viewport you'll see a plane with an OSL noise displayed.
In Slate you'll see a map tree that is fed into the diffuse channel of a Standard Material and a Corona Material.
The plane has the Standard Material assigned, make sure viewport is set to HQ mode to display OSL correctly. Now assign the Corona Material to the plane and it will display a wrong result. It will only match the Standard Map when rendered, but we need it to display correctly in the viewport.
If you now remove the OSL noise map named 'UVW modulator' from the OSL UVW Channel map it will match the result of the Standard Material. For some reason, Corona Mtl can't display OSL correctly in the viewports if UVWs are modulated.q