Neither Update or Fill Import options fill data in checkboxes or select fields

When custom data is generated as a checkbox or select field, the update / fill operations do not function.

Example - if you have 3 checkboxes - green, blue and red, assume the data has already been imported at least once with the field "green" checked. Attempts to import the data to update a record where green AND blue were selected, neither the update or fill import features add "blue" to the record.

I'm using the 1.3 revision 4308.
thx!