LG ultra wide screen

Finally upgraded to Sierra today only to find my brand new LG ultrawide no longer is supported? Hopefully we'll see an update soon with a fix.

I had this same issue. If you leave the laptop open when connecting to the display it should work. Let me know if this fixes it!

Does not work with my LG ultra wide, not full "ultra wide" resolution

Your recommendation helped me patch this issue as well. I had to set the pixel clock to 159.75 for it to work with on my MBP.

Latest update 10/27/2016 does not fix this problem!

Can confirm. Does not work for me either.

Somehow my LG widescreen is now displaying the appropriate 2560 x 1080 resolution under 10.12.1. I did install NVIDIA drivers using this:

http://www.nvidia.com/object/macosx-cuda-8.0.51-driver.html

After I did, I couldn't get any output at all to the external monitor. Then, I used the NVIDIA menu to switch back to the OS X default driver and not only did I get output back to the external monitor but it also went to the widescreen resolution.

How did you get an nvidia menu?

I installed the CUDA drivers - but I just get a panel under System Prefs -> Other ->CUDA

There is no option to switch drivers.

Did you perhaps install the nvidia drivers (not CUDA)? If so - where did you find the right version. I tried the latest I could find, and it says it is not compatible

The little menubar item installed itself when I installed the drivers. There may be other versions out there but this one was able to install for my MBP (11,3) - Retina Late 2013. I may have posted a different link than the one I tried. Here's the correct link for what I tried:

http://www.nvidia.com/download/driverResults.aspx/110124/en-us

OK - I am on the latest 10.12.2 beta, and I don't think nvidia drivers are available.

The very latest beta, plus changing the cable from a DP->HDMI to a HDMI->HDMI solved my LG Widescreen issue

This worked for me today.