To Do List Changes on Mobile 

Alliant University does not maintain the Canvas mobile app.

Canvas has updated the way the To-Do list works on the mobile app

FIRST - Select the FILTER Icon on the app.
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SECOND - Set the date ranges to some time in the past and some time in the future.
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Documentation from Canvas:
community.instructure.com/en/discussion/664272/to-do-list-improvements-on-mobile