I've had the LG 34BK95U-W UltraFine 34" 21:9 5K 2K display for several months now and everything has worked fine with both my 2017 MBP and my 16" MBP. However, after the 10.15.4 update things have gone haywire with sleeping on the 16". I've pasted what I submitted to Apple as a dev bug report in the event anyone else is in the same situation. I've not submitted anything to LG because there were no issues with 10.15.3. And yes, I'm aware there were issues with the 2018 MBP.
One addition is that I'm going to test with graphics switching disabled and running only the AMD 5500M to see if that makes a difference.
*****
When the 16" MBP goes to sleep the display no longer sleeps/behaves as expected as it did under 10.15.3. Below is what occurs:
- The MBP desktop is no longer displayed as it is sleeping but the display is not, rather it changes to a dark grey but still produces illumination.
- When trying to wake the computer via external keyboard or mouse, system sounds are heard on the MBP but the display does not change or wake up and must be unplugged and plugged in again.
- The display's joystick button also becomes inoperable.
- Opening the MBP displays the desktop on the MBP but not the external display.
- Attempts to unplug the Thunderbolt cable and reconnect at either the MBP or display produce no results, the display remains greyed out.
- Only rebooting the display brings it back.
When putting the MBP to sleep via the apple menu (as opposed to the system sleeping automatically) the computer goes to sleep and the display shows the message that no signal is detected and that it will enter power saving mode shortly which it does. I am then able to tap a key on the external keyboard which wakes both the display and the MBP.
Again, there were NO issues with 10.15.3 and there has been no display firmware update since updating to 10.15.4.
One addition is that I'm going to test with graphics switching disabled and running only the AMD 5500M to see if that makes a difference.
*****
When the 16" MBP goes to sleep the display no longer sleeps/behaves as expected as it did under 10.15.3. Below is what occurs:
- The MBP desktop is no longer displayed as it is sleeping but the display is not, rather it changes to a dark grey but still produces illumination.
- When trying to wake the computer via external keyboard or mouse, system sounds are heard on the MBP but the display does not change or wake up and must be unplugged and plugged in again.
- The display's joystick button also becomes inoperable.
- Opening the MBP displays the desktop on the MBP but not the external display.
- Attempts to unplug the Thunderbolt cable and reconnect at either the MBP or display produce no results, the display remains greyed out.
- Only rebooting the display brings it back.
When putting the MBP to sleep via the apple menu (as opposed to the system sleeping automatically) the computer goes to sleep and the display shows the message that no signal is detected and that it will enter power saving mode shortly which it does. I am then able to tap a key on the external keyboard which wakes both the display and the MBP.
Again, there were NO issues with 10.15.3 and there has been no display firmware update since updating to 10.15.4.