Unable to change CL in FIT run

When running a calibration FIT run on RORB (v6.45), the user is able to change values of kc, m and IL. But for some reason, CL is greyed out and RORB does not allow for changes to that value within the program.

A workaround for this is to save the run details to a parameter file (.par), then open the .par file in a text editor and manually change the values there

I believe this is a bug as I think the user should be able to change CL within the program without this workaround