Automation Engine does not read the metadata of certain files created or modified by ArtPro+. Why is this?
This will be the case of regular PDF files (non-Normalized). These files are saved in PDF+ file format by ArtPro+, which means their metadata is placed in public dictionaries of the PDF, and not in private ones like Normalized PDF XMP does.
On the long run, this will mean broader compatibility as well as avoiding normalization steps through the workflow. Meanwhile, Automation Engine can't read this PDF+ metadata yet, what answers this question.
Support of PDF+ metadata on Automation Engine is expected to arrive on future releases of version 16.