omit creation of tiles for no-data regions

[ThomasHalwax]

I've created a very similar tutorial terrain-rgb but still have issues with no-data regions. We both set the value of rgb(0,0,0) to -10000 and I expected rio to omit all regions with this value. Unfortunately this does not work and my mbtiles container is full of tiles with an elevation of 0.

Do you see the same results and if not can you please give me a hint where to pay attention to?

Thank you for your help!
Best regards, Thomas