No worries—everything is working as it should! The column with the RunningMan logo is the only high-frequency (HF) driver column included with this product. The other two columns are simply height extensions or "spacers" designed to raise the HF driver column to ear level.
If you're curious, you can hold the HF driver column sideways up to the light and see its speaker drivers. On the other hand, holding the spacer columns up to the light won’t show any drivers at all!
As long as the high-frequency sound is coming through the HF driver column, your spacers are doing exactly what they're meant to do!
For more information or questions about Mackie products, please contact us here.