Has anyone been able to generate a report of all the expense items that have been rejected or sent back to the employee via the Send back Expense checkbox available on the expense form?
I don't think this is something that can be report on. I searched to see if there was a data item labeled "Send back expense" in the data warehouse, but nothing came up. So, I'm thinking that there isn't a way to build this report. I am not 100% sure, but @TRedman might be able to confirm or deny this. :-)
If an expense report is split, a portion is approved and sent on for payment, and a portion is returned to the employee. This creates an addendum expense report. The new report has the same report name, with the word "Addendum" before it. The Addendum report has a new Report ID & Report Key, but the originals are listed in the comments or audit trail. There is not a direct connection within the data between the two reports, but you can identify the original through those data points. It is not a clean report, but you could build something which the report name contains Addendum. This won't be a 100% accurate, as a user could change the name of the addendum report but could get you close.
Hope that helps!