Unable to select 'categories form' from of source field when using grouped values in Dashboard elements

[AvishekPaul1]

When utilizing Categories from Grouped Values for data options in an ArcGIS Dashboard element, it is not possible to alter the source field menu.

I found some short tutorials that explain what's below. (Link: https://www.esri.com/about/newsroom/arcwatch/create-your-first-dashboard-with-arcgis-dashboards/)

From esri tutorial

However, I am unable to do the same. My ArcGIS Online dashboard does not allow me to select the Category field from the drop-down list.

Screen shot from my dashboard

Does anyone know how to resolve this issue, or is it potentially an ArcGIS Online dashboard problem?