Content length mismatch

Serving a website behind ARR and URL Rewrite with SSL offloading in place.

Using the Microsoft ReportViewer control for SSRS.

In IE only, content is truncated when the ReportViewer returns content; using Fiddler I get the following message about a protocol violation:

"Content-Length mismatch: Response Header claimed 1767884 bytes, but server sent 1772317 bytes."

Removing ARR, URL Writing and SSL ofloading from the picture, the content is returned in full, as expected, no errors in IE.