If I save a KST session with a curve which has the "Ignore in automatic axis range calculations" ticked and then exit KST and reload the KST session, the setting becomes unticked and the curve values are used in axis range calculations.

Steps to replicate:
RMB on plot, choose Edit
Select curve in plot then Edit
Tick option to "Ignore in axis range calculations"
OK to all dialogs
Save KST session
Close KST
Open KST
Open session file
You should see from plot that the range has been calculated differently, otherwise
RMB on plot, choose Edit
Select curve in plot then Edit
Option to "Ignore in axis range calculations" is unticked