What kind of value list are you using for your check box?
Are you using the same exact value list on both layouts?
If even one character of the data inputted differs from the list of values assigned to the check box, none of the boxes will appear to be selected. To temporarily analyze what data is actually being entered in this field, you might change the setup back to edit box and inspect the data actually being entered. click in the field to check for non-printing characters such as a space.