Atril fails to print double-sided properly

[MR Zenwiz]

marbase 4.15.0-47-generic #50-Ubuntu SMP Wed Mar 13 10:44:52 UTC 2019 x86_64 GNU/Linux
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.2 LTS"

Atril version 1.20.1

I have a Brother HL-2240D laser printer that has been printing double sided on demand for years.

When I set the printout to go double-sided along the long edge, I expect to see print on both sides of the page.

In the last two weeks, printing a PDF using Atril sends the printer double sided commands, but the print only appears on one side of each page. It does the reverse feed to print on side two, but side 2 always comes out blank.

[MR Zenwiz (mrzenwiz)]

This also happens in 20.04 - focal fossa.

Thanks.