Hi Tait,
Thank you for sending the file.
We were able to identify the cause of this error message, but do not have a solution for the problem. It is an unusual situation in which somehow the name of the "grid_power" variables for one for one of the 44 parametric runs in the file did not get saved properly.
That may have been caused if the file saving process was somehow interrupted. Are you saving the .sam file on a network or local drive?
Best regards,
Paul.