Screen rotated 180 degrees - don't know why

[kibob]

Hello everyone,

My wife is using a MacBook Pro 13" connected to an Elgato Thunderbolt 3 dock and an external LG 34" Ultrawide monitor (connected to the dock via DisplayPort).

Around once a week when she wakes the MacBook Pro from sleep, the external Ultrawide screen comes up rotated by 180 degrees! The built-in display of the MacBook still is oriented normally, though. I just found out that when this happens, the monitor actually shows 180 degrees orientation in the system settings. When changing that back to "standard", the screen orientation is fixed. But why is macOS changing the orientation setting on wake up? It only happens when waking up the MacBook (but not every time), and never during normal operation. This behavior is happening for quite some time now and throughout several macOS releases (running latest Mohave atm). It even occurred with a different MacBook Pro connected to that dock/monitor. Reinstalling the OS did not help so far.

Can someone give us a hint what we might be doing wrong?

Thanks!

 

[chscag]

How about when you connect the LG direct to the MacBook Pro, does it do the same thing? I don't have any experience with that particular dock, but it sounds like it might be causing the 180 degree rotation.

 

[kibob]

Thank you for this proposal. We don't have another TB3-to-DisplayPort adapter. Can an external device on TB3 indicate an orientation of attached equipment to macOS so that it configures the rotation in System Preferences automatically? Maybe the dock reports a wrong orientation of the display to the OS? I don't know if that is possible at all, though.

Or can it be an accidentally used keyboard shortcut that triggers the orientation change during wake-from-sleep?