Okay, so, in hindsight I maybe should have thought of this, but apparently the absence marker absolutely refuses to be lit by candles; for example, a candle sitting immediately next to a loot item on a table (AI standing a couple feet away, directly facing) will not light up the absence marker (the item used in this case was the moveable_loot_chalice). However, a light set to 75 brightness value whose radius extends only about 8 units beyond the loot item (so the chalice was almost totally in shadow) is apparently enough for the marker to be lit and the AI to see it. The ambient_world was set to 4. Now to try to set up the painting.. Btw, is there a way to modify the candles so they would light up the marker? I'd much prefer that to another sort of light in this area.