Seeing this on the latest experimental build (v0.8.7 (b613)), so not sure if this is appropriate here because of that.
When attempting to drag a transport under the ramp piece, it is allowed within the first two piers and the "abutment" (counting from the base of the ramp) and not within the space to the base side of the same piers. See the attached screenshots showing an attempt at dragging a pi…