Unable to delete expense report with an attachment

We have been running tests and discovered that if an expense report has an attachment, it can't be deleted.  We are getting an error message that state the attachment failed to download. See attached document for a screen shot of the full error message.  If you return to the document and delete the attachment, re-save the document, then go back to delete expense report, it will work as expected.  Why do we have to delete the attachment before deleting the document? Why are we getting an error that says the attachment failed to download? Anyone else experiencing this issue?

Regards,