This incident has been resolved.

A fix has been implemented and we are monitoring the results.

Due to an issue on Facebook's side, some of the attachments that subscribers are uploading in response to your bot are not being delivered to Live Chat. Facebook is investigating the cause of the issue. Hopefully, it will be resolved soon.

You can follow the progress on Facebook's help portal using the link - https://developers.facebook.com/support/bugs/393441492018560.