You do mean the 2D HUD in the 2D cockpit? The image looks like it's the 2D cockpit. I'll try and answer it for that.

Press Ctrl+Space to see if it changes the pitch of the view in the 2D cockpit. It changes the view to parallel with the ground, and the green circle and the red calibration circle only align after I do that. I have to do that to the default C172 before calibrating the 2D HUD in the 2D cockpit.

Mark