Can you plan flights just along a Y axis (vertical only)?

A circle with a diameter of 2m has a circumference of 6.28m.
The minimum 3d distance between 2 waypoints is 0.6m.
This roughly means that this circle may have a maximum of 6.28/0.6=10 waypoints.
Most likely ALL your waypoints are too close together.

The Mission Hub does NOT check for this, the Litchi App does.

Also check this thread: