When I create a Graph in LabTutor, why does my Curve Fit just appear as a vertical line rather than fitting the data?

This is a known bug with the graphing functionality of LabTutor / LabAuthor, specifically with the commonly-used Linear Curve Fit option. This occurs if the values being plotted are smaller than 1x10-2 (less than 0.01).
To resolve this issue, amend your protocol to read in smaller units (resulting in larger values).
For example, if you are working in Volts and your values are 0.005, 0.007 and 0.009, change your units to mV by multiplying the value by 1000, resulting in a value of 5, 7 and 9 (mV), and change your graph and table labels appropriately.
Please see this Experiment for a direct example of this issue, and how it can be resolved (opening this Experiment requires LabTutor / LabAuthor 4.5.2 or newer).