Just to clarify:

The recommendation to have the Infinite light and the Diffuse IBL light in the same place was for the situation where you are not using an image with the IBL, but just assigning the lights to the 'Sun' and 'Sky' lights respectively. This is to ensure consistency in the lighting calculations, as if you'd assigned a single light to both.

If you're using an image with your IBL then the Infinite light (if you need on at all, of course) should be positioned to cast light from the same direction as it appears to be in the image, which is most likely a completely different position to that of the IBL light.

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