Changing agent height

Back in Edit mode, you can press 'H' cycle through a sequence of different agent heights.
The current height is displayed at the bottom of the window.

Change the height to the smallest value, and switch back to Test mode.
Place the agent, as before, at the centre of the bridge.
(The agent should now be drawn at the new height.)
As before, select a target on the opposite side of the table.
With the new height value, the 3D content processing will leave valid ground underneath the table, and the agent should be able to pass between the table legs.

The shortest agent fits underneath the table.

The shortest agent will also fit underneath the fence sections, elsewhere in the scene.
Try generating for the tallest agent, also. This agent doesn't fit underneath the smallest of the three arches, and will choose paths around that arch.