How to query date of entry addition to the Materials Project?

Based on the mapidoc, I was hoping to query the creation date of a Materials Project entries based on the property fields: ‘created_at’ or ‘updated_at’, or to use the date information under ‘snl’/about/created_at. However, none of these worked for me. Is there a different way to get the creation data for each entry?

Wenhao Sun