I'm in the same boat - neither incandescent nor LED bulbs were working for me. At least one piece of this puzzle is the floating stock headlight plug that you're left with after using the Koito harness.
@HemiAlex hipped me to a small module from HID Kit Pros - it plugs into that empty headlight connector and I would guess it's a dummy load.
I got that installed and now my high beam indcator works but is very dim. You can see it at night, but not at all during the day. Oddly enough, only incandescent bulbs are working. LEDs don't come on at all. In the photos below, the indicator is on in the daytime shot - clearly bot visible at all.
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