Nicolas, I suspect you may be seeing 86011 rather than this bug. xresprobe tosses the highest resolution and reports only up to the second-highest in some circumstances. See my comments there.
Dave, Oliver, and siggi, can you please attach your Xorg.0.log and xorg.conf files, and the output from ddcprobe and xresprobe <driver>?
Nicolas, I suspect you may be seeing 86011 rather than this bug. xresprobe tosses the highest resolution and reports only up to the second-highest in some circumstances. See my comments there.
Dave, Oliver, and siggi, can you please attach your Xorg.0.log and xorg.conf files, and the output from ddcprobe and xresprobe <driver>?