Multiple Response Survey question

Hello,

Faced the same thing but not for such huge amount of surveys. You could:

1. go to your Queries
2. duplicate the Query
3. Delete all columns except IDs and 1 Question with checkboxes
4. Select all collumns with answers to Checkboxes
5. Go to the Transform >> Unpivot columns
6. After that filter last column to disable zeros
7. Delete last column
8. Close & Load

You will get a table with ID and Column, lets name it "Selected Checkboxes" 

Throw IDs and Relationship type "1 to many", plus "filter in both directions", you could use slicers/demographic data from the main table vs Checkboxes answers.

P.S. Doing in this way also gives you an opportunity to use Checkbox question as Slicer to the main table data.