I recreated the Article list demo delete action in my own form and got the below debug. I then tried the delete data action in the Article list demo and that also failed. I think this may be a bug?
Array ( [chronoform] => currscholapp_committee [gpage] => DeleteApp [aid] => 574 [Itemid] => 491 [option] => com_chronoforms7 [view] => form )
Array ( [delete_data_569] => Array ( [result] => Data deletion failed! [log] => Array ( ) [var] => false ) )