Hi, sorry for the late reply — I didn’t set myself up to receive email notifications. That’s been rectified.
The cause of an ‘undefined index’ notice from PHP, in this particular case, is a request for a value from an array $metadata['pb_bisac_subject'] which is empty, or not defined. At the bottom of the page ‘Book Info’ there is a text field with the label ‘Bisac Subject’. Putting a value in that field will prevent the PHP notice from appearing in your log files.
