I noticed the TileGeomAvg function has changed since an earlier version of M9 to include an argument for image channel (3 args now) but the Transfer DEM Terrain Heights to Areas in a Drawing tutorial hasn't been updated (2 args).
Good eyes! Do you want to send that in as bug report or would you prefer I did it?
Not so much good eyes but persistent when trying to learn!
I'm more than happy for you to send that as a bug report - thanks Dimitri.