Thank you for your reply Daniel Oberbillig.
I attempted to recreate the error with sample data so I could publish it here. Unfortunately I was not able to recreate it with the sample data, so there is nothing wrong with the script itself.
I was going through every setting, formula and object on my dashboard looking for any inconsistencies and finally found 1... I am using a hideprefix to prevent some selections from being displayed in the Current Selections object. After saving the dashboard, the fields containing the hideprefix would no longer be available when the dashboard was reopened.
I promoted the tab containing the data islands with the hideprfix to the beginning of my script and the problem seems to be solved now. I appreciate your help!