Hi @colinwitt , thanks for your post!
For scorecard charts, the Date range dimension field will appear if your data source has a valid date date dimension (per the Scorecard chart documentation). If you do set a date range for an individual chart, it overrides any input from the date range control (per the Date range control scope section on the Date range control documentation page).
I wonder if you could try setting the date dimension that the scorecard responds to as the Date range dimension for the entire report or page. The Set report date ranges documentation page provides instructions for how to set that up.
I hope that is helpful!