You can see if your PebblePad workbook is submitted for assessment by going to your assets and looking for the clipboard icon:
A workbook that has been submitted for assessment will show the clipboard icon blue and says 'Shared with 1 workspace'.
If you see the clipboard icon is greyed-out, then you may have accidentally created a duplicate or recovered version of your workbook. Have a look at the other workbooks in your assets for one that has been submitted for assessment and make sure you are only working on that workbook. Check to make sure your submitted workbook is complete and up-to-date, copying over any text or attachments you may have added to the duplicate version.