Great. Now we're getting somewhere.

Set your non-IBL lights to white. You said you have one gray main light and one spot light. By main, did you mean infinite? The light types are infinite, point, spot, and IBL. There is no "main".

Drop the spot light for now. Set your main (infinite) to 75%, white.

Set your white IBL to 15%. Set the IBL Contrast (in the material room for the light) to 1.

Your figure will still be dark, but that's a valid light setup. We will then GC your figure and all will be well.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)