When uploading attachments from mobile, the applications will first sync the parent object (Activity, Smartform, etc.) and then send the attachment; This means there could be a delay between the time the object reaches the cloud and when the last attachment linked to this object is uploaded.
If you are creating reports from Smartforms instances, please consider using a business rule with a delayed execution to ensure all attachments have been uploaded before the report generation.
There are two ways to generate the PDF when closing checklists:
1.) via company setting ChecklistReportingEnabled - this cannot be delayed and will execute as soon as the Smartform is closed, meaning you could miss some of the attachment content when generating a report.
2.) via a Business Rule a delay can be added to accommodate for the time it will take for the attachment to reach the cloud. It is not guaranteed that all the attachments are in the cloud by the time the rule executes. SAP is reevaluating the approach and investigating how it will be made more robust, so a delay is not needed on the reporting. More updates will follow. For now, the delayed business rule execution is the recommended approach.
Note: Attachments are processed at the end of each differential sync, so if you have a long diff sync time, please take this into consideration when creating your delayed execution rule.