Yes, I too think, it´s a bug. We had this situation before and the support said, they couldn´t find anything. When I try to submit to groups, when uploading new pics, I get error messages "there has been a problem submitting to groups" or something and it doesn´t let me finish the submission process, until I uncheck all the tick-boxes for the group-submissions. After that, I find out, that the picture HAS been submitted to about half of the groups, although the tick-boxes were unchecked. Strange...