Thanks for sending the scene. I don't have any absolute answers, but hopefully the following information will help:
1) The Revit emitters (containing the IES distribution) in your scene are geometry items - which all have the same Revit Material. Octane is converting the Revit Material (which is called "Light-Metal") to an Octane material, and if you look at the Revit Material, you will see no evidence that it is an emitter. Emitters in Octane are defined by Material, whereas in this case the emitter in Revit is defined in the Geometry item parameters.
2) When the Octane plugin converts the "Light-Metal" material to an Octane material, there is no way for the plugin to determine which Revit geometry items are using that Revit Material - and therefore it does not know that the Light-Recessed family is using that material, and therefore cannot read the Photometrics data from the Light-Recessed family.
So in summary, the Octane plugin will convert any emitter data from a Revit Material (because there is a one-to-one correlation between Revit and Octane materials). But it will not convert emitter information from the Revit Type properties.
So in this case you really need to create 4 Revit materials (Light-Metal-1, Light-Metal-2, Light-Metal-3 and Light-Metal-4), assign them to the 4 different emitters, and then edit the resulting Octane materials to set the applicable IES file. You can shortcut this by creating a single Emitter material, and "Export Material" that material and then import it into any other emitter materials in the scene.
I hope that helps.