Reconstruction.json - Covariance field is empty

Hi, I am new to the opensfm project and was hoping for help on this aspect. So when I ran the reconstruction pipeline, I saw my covariance field was empty.

Is there any way I can check why it’s empty? Any directions will be helpful or by any method I can tap into the covariance field - a potential workflow to achieve that or any directions to get that will be helpful.