My elaborate comments with plots are not posting for some reason.
Yes, I am using a mode expansion monitor and dividing by purcell factor. When I use a finer mesh, the transmission values are still greater than one.
I would also like to point out that in the Lumerical youtube video "Dipole Source in Ansys Lumerical FDTD – Lesson 6, Part 1", they mention that the purcell factor needs to be multiplied for renormalization. What do you think about that?
I was unable to find the setting "set the recording frequency to be broadband" in my mode expansion monitor. It would be helpful if you could share a screenshot of the settings window where I can find that.