Hi Jeff, thank you for your question.
Assuming by "new prompt" you mean the new date range you selected in the filter on the canvas, then I believe you may have encountered a defect. The Apply button should become enabled whenever you modify the range.
I would encourage you to log a ticket with IBM Support, if you have not done so already.
Just out of curiosity, if you apply a date range in the 'This tab' of the filter tray, then 'Add to canvas', do you still experience the same issue in you modifying the date range?
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Brennan Fox
Product Quality @ IBM Cognos Analytics
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