That could be, can you shoot me that option one more time, I accidentally
deleted your e-mail, I found machines that are still broke and they have different versions of the libs than the ones that are working.
-rrxinerama to disable Xinerama handling through RandR.
libnx-x11-6 on the machine(s) that is working is version
2:3.5.99.9-0.1+git20170830.2839+14.04.release 1.
Maybe Ulis changes were not part of this release yet (and, by extension, the code still used the old Xinerama faking mechanism without relying on RandR).
Mihai