JsonValidationError List 'attachment' is undefined on object
When performing a manual push or pull action, the attachments are not being pushed/pulled to Jira upon issue creation.
The error seen when attachments data is not fetched:
In Jira, click on the gear icon on the top right of the navigation bar > Issues → select the Field configurations (under Fields section) option from left sidebar.
Select the field configuration name > search for "Attachment" in the search box.
If the Actions section shows the word "Show", this means the attachment field is hidden.
Click Show to unhide the attachment field.
Check if the field is linked to the correct screen. If the screen does not show up, read this documentation to link the attachment field to the appropriate screen.