Comment 8 for bug 1726538

further update - prior to 17.10, my logon routine was to boot up my laptop with the screen open, then as soonn as my 2 monitors picked up the screen image during the boot up process, I closed my laptop screen fully shut, and completed the rest of the boot up process, including entering my logon password on the montiors, with the left one showing as my default primary monitor. This worked every time.

Since 17.10 this big 1726538 has occurred. I discovered today though that if I keep my laptop screen fully open throughout the boot up and logon process and type my logon password into the logon prompt on th laptop screen, then let the boot up process run fully, with the laptop screen open, when the boot up process ends the monitors are correct with the primary default monitor on the left and bug 1726538 does not occur. I close my laptop screen fully then and all is well. No issues. However if I close my laptop screen part way through the boot up process, before it is fully finished, the bug reappears and my montiors are switched round again.

For me this is a decent work around fix, although I'm not sure it's working as designed so probably still valid to keep this bug open and investigate some more.