LG UltraFine 5K monitor - external devices not detected

I am having this issue on my 13" non-touch bar. Monitor is awesome but the USB hub seems to not renegotiate when I disconnect and reconnect after a meeting. Extremely annoying. NVRAM and SMC reset doesn't do anything.

Hi, I have this same issue repeatedly. I'm on a 13inch TouchBar MBP connected to an LG 5K Ultrafine display. I've done the SMC and NVRAM reset. Sometimes the USB devices attached to the monitor power up, sometimes they do it. It's proving rather frustrating given the cost of all of this kit. I never had issues with my old MacBook Air connected to an Apple LED Cinema Display.

Please advise. Seriously considering returning the whole lot at the moment as it's terribly buggy.

I have the same problem with a Logitech USB dongle for the Mouse, Reboot, SMC, NVRAM will not consistently solve the problem, sometimes it works, sometimes it doesn't, I think this is a problem with the connection that once the MBP is plugged back using the supplied Thunderbolt 3 cable the monitor will not power the USB-C hub.

I have the same issue.

When first connecting everything works.

When I need to disconnect my laptop, I eject any drives connected to the monitor.

Then when I reconnect the laptop, it's 50/50 on whether the drives connected to the monitor reattach.

This is incredibly frustrating, especially for such an expensive monitor.

I'm hoping their will be an update to address/fix this.

Some have reported this issue and I've seen a version of this with my dual lg ultrafine 5k setup too. It seems to be that either the laptop or the monitors do not handle hot-swapping very well. I've seen that when unplugging the monitor from the laptop and then reconnecting, it doesn't consistently re-initiate the connection.

I've gotten around this by rebooting the laptop, but this is an annoying issue to be sure.

I have the same issue. I am using 15" MBP TouchBar and LG UltraFine 5k monitor. My ethernet and usb connections out of the back of the monitor are not active when I reconnect my laptop. I have to restart with the laptop connected or unplug and reconnect the usb items to the back of the monitor.

Either solution is unacceptable and does not make me feel good about the thousands of dollars spent and weeks of waiting for this new set up.

Same problem here, as all others have stated. I'm using a Belkin USB-C to Ethernet Gigabit adapter. 50/50 chance of it reconnecting after I remove then return my 15" MBP With TouchBar.

I was using another adapter type before and returned it, thinking problem was with the adapter. Turns out, it's the LG UltraFine 5K display or int's interface/interconnect with the MBP.

Agreed, very annoying! My Ethernet cable is connected to the monitor via a USB-C adapter. It works but fails to be recognized when connecting the MBP 15" to the monitor more often than not. I hope someone (Apple or LG) fixes this, as it is a major flaw.

I am having a similar issue on an older Macbook Pro and I don't think it's an LG issue, because I recently purchased a Dell 4K monitor which I have a PC(DVI) and a Macbook(HDMI) connected to. When I first connect my Macbook to the monitor, my USB devices work fine(I have a keyboard/mouse connected to one USB port and my iPhone cable connected to the other). However, after I switch the input to the PC, the USB ports on the Macbook stop working. I've tried closing the lid of my Macbook, going back and forth between inputs, disconnecting the HDMI cable from the Macbook, etc. but the ONLY thing that works is restarting my Macbook.

I should not have to restart my Macbook every single time I swap inputs on my monitor in order for my USB ports to work. How can I resolve this?

I tried the NVRAM reset and did not solve the problem. If I attach a late 2016 15" MBP (running) to a 5k LG monitor, more often than not it does not detect an ethernet cable connect to one of the spares USB-C via a Belkin adapter from the Apple Store; it thinks the cable is unplugged...

Detaching the monitor from the laptop reconnects, but it may take several tries.

This is unacceptable!

Dear MoonJ,

Is there any way you can make this thread unsolved again. Your solution appears not to be working for most of the people posting in this thread (including myself), and the fact that the thread is marked as solved falsely indicates that this problem can be consistently fixed. Disconnecting and reconnecting the display gives a 30/70 percent chance of the peripherals being detected. Since I reconnect approximately 15 times a day you could imagine this is not a very pleasant experience.

It would be nice if Apple and LG could somewhere list all the problems occurring with this display and also communicate whether they intend to fix these issues. Currently for me it is really unclear whether I should return this display because this problem is never going to be solved, or if I should wait for a software/firmware update.

Kind regards

Arthur

I also have the same issue. Disconnecting and reconnecting the laptop from the LG 5k monitor. All accessories attached to the monitor's USB-C ports are not recognized. Have to either restart the computer, or unplug each attached device.

LG Screen Manager is an application that provide screen split and monitor software update feature.

This software is compatible with below LG monitors only.

Supported monitor: 22MD4KA, 27MD5KA
Supported OS: macOS 10.12

http://www.lg.com/us/support-product/lg-27MD5KA-B

This is still a problem in High Sierra. If anything it happens more regularly. There is no software update available in the screen manager, it says "(3.01,1.11,5234,3.00,0.1d) The software is currently up to date". The accepted solution does not work. Are you going to fix this Apple/LG?

I contacted LG support, their response was:

I have discussed this with our technical team, the issue seems to be with the Mac not recognising the devices. We have raised this with Apple and they are looking into a resolution for this issue. We would advise to contact Apple directly also as they may be able to provide more information on this.

I contacted Apple support who had no idea about this issue. Their eventual recommendation was to reinstall macOS. This seems very over the top and I doubt it would work. I have reported it as a bug. If you have the issue I would suggest reporting as a bug and/or contacting Apple support to raise it up their list of priorities.