Official comment
Did you select the images and come back to step 2 to turn that setting on as the little black box says?
All maps we produce are 3D. The Full 3D option is really only intended for modeling a single structure or small area. The only difference in the processing is that it renders the overhung surfaces.
https://support.dronesmadeeasy.com/hc/en-us/articles/207855366-Full-3D-vs-2-5D-Processing
If you just need a 3D model file output check the 'Full Resolution OBJ' box.