Cannot "Call a Script" for a Bot's Task

[StephenHind]

I am working on an AppSheet app that uses a Google Sheet as it's data source.  I want to add a Bot to call an Apps Script but when I get to definign the Task the "Call a Script" option is disabled and the mouse-over/hover tooltip says "Google data source required to use Apps Script", but it is a Google data source as it's a Google Sheet.

Any ideas?