Exporting participant data does not deal with custom yes/no fields correctly (on joomla)

I have an issue with exporting custom data for event participants with Joomla! 3.4.5 and CiviCRM 4.6.9.

Only the first row is presented correctly.

1. create a custom field set for participants - add a new field of type yes/no (I called it "testyesno")

2. create a new profile and select the above participants field name "testyesno" for inclusion.

3.create an event that includes the above profile for online registration

4. add a number of registered attendees, for some, select YES and others, NO for the custom data field

5. list all registered participants for the event and select export as csv

6. only the first row of data will be presented properly with a YES or NO - other rows display as blank or 1