LG Display 4k No longer works with HDMI Adapter Pass through

[smallcoffee]

Just wanted to share this datapoint.

I have the LG display. 4k. USB-C from the display to an M1 MacBook Air no longer functions if passing through to a USB-C HDMI adapter.

(Why am I doing this?)

External mouse using a USB-A adapter, figured I'd just use the one port for both and keep the other port free.

I've had issues with this display with iPad Pro too. Apple really pissing me off with this.

 

[Maconplasma]

You said it no longer works. What makes you so sure this is a fault of Apple's and not the cause of a possible corrupt file in your setup? You're getting mad at Apple but you're not stating a reason as to why would they want to remove functionality. What would they benefit from by doing that?

 

[smallcoffee]

You said it no longer works. What makes you so sure this is a fault of Apple's and not the cause of a possible corrupt file in your setup? You're getting mad at Apple but you're not stating a reason as to why would they want to remove functionality. What would they benefit from by doing that?

Basically a poor history of software support for this monitor. “Corrupt file”? Lol.

 

[Maconplasma]

Basically a poor history of software support for this monitor. “Corrupt file”? Lol.

Apparently you have all the answers so I don't see the point of this thread. Makes sense why nobody else has responded to it. 🙄

 

[joevt]

Just wanted to share this datapoint.

I have the LG display. 4k. USB-C from the display to an M1 MacBook Air no longer functions if passing through to a USB-C HDMI adapter.

(Why am I doing this?)

External mouse using a USB-A adapter, figured I'd just use the one port for both and keep the other port free.

I've had issues with this display with iPad Pro too. Apple really pissing me off with this.

Which LG 4K display?
Which USB-C HDMI adapter?
If the display has a USB-C input, why are you using HDMI?
What is the external mouse connected to?
What does "use the one port for both and keep the other port free" mean? Need more explicit qualifyiers/identifiers/adjectives for each object/noun.

 

[smallcoffee]

Which LG 4K display?
Which USB-C HDMI adapter?
If the display has a USB-C input, why are you using HDMI?
What is the external mouse connected to?
What does "use the one port for both and keep the other port free" mean? Need more explicit qualifyiers/identifiers/adjectives for each object/noun.

• THE LG 4k display. The one Apple sells on the Apple Store online and promotes.
• The Apple HDMI, USB-C, USB-A combo adapter (3 total inputs) that connects to a Mac using USB-C.
• I'm not using HDMI, the adapter has HDMI. I'm using the USB-C passthrough.
• It's connected using Bluetooth to the USB-A adapter, which is hooked up via USB-A (and working) with the HDMI adapter.
• There are two ports on the M1 MacBook Air... I'm keeping the second port on the laptop free and using the HDMI adapter to connect the monitor via USB-C and the USB-A bluetooth receiver for the mouse.

 

[smallcoffee]

Apparently you have all the answers so I don't see the point of this thread. Makes sense why nobody else has responded to it. 🙄

I'm sharing as a data point, not asking for help or advice. This is so others know they are not the only ones experiencing this problem. Attributing it to a "corrupt file" isn't helpful and there is no evidence that such a thing caused the problem or would cause the problem. What file could be corrupted that causes a monitor to not work with a Mac? That would be pretty concerning. It's more likely that LG and Apple are just not doing well with keeping firmware up-to-date and coordinated. You can roll your eyes all you want, but it is what it is.

I've also shared how this monitor doesn't work via USB-C with the iPad Pro. This is another documented problem. You can look up my post history to find the thread and the shared experience with this not functioning.

 

[joevt]

• THE LG 4k display. The one Apple sells on the Apple Store online and promotes.
• The Apple HDMI, USB-C, USB-A combo adapter (3 total inputs) that connects to a Mac using USB-C.
• I'm not using HDMI, the adapter has HDMI. I'm using the USB-C passthrough.
• It's connected using Bluetooth to the USB-A adapter, which is hooked up via USB-A (and working) with the HDMI adapter.
• There are two ports on the M1 MacBook Air... I'm keeping the second port on the laptop free and using the HDMI adapter to connect the monitor via USB-C and the USB-A bluetooth receiver for the mouse.

As far as I know, the USB-C pass thru of the Apple USB-C Digital AV Multiport Adapter is not for USB data or DisplayPort data - it's only for charging. That's why the icon next to the USB-C female port on the adapter is not a USB or DisplayPort Alt Mode icon (like on the HP Thunderbolt Dock G2).

Connect the Bluetooth adapter to one of the USB-C ports of the LG UltraFine 4K display. You should be able to use the Apple USB-C Digital AV Multiport Adapter to convert the USB-C port to USB Type A.

On an Intel Mac when the LG UltraFine 4K is connected to a Thunderbolt port, you can connect the Apple USB-C Digital AV Multiport Adapter to the second Thunderbolt port of the LG UltraFine 4K and get HDMI output for a second display. But an M1 Mac only supports one display from Thunderbolt, so you might as well save the second Thunderbolt port of the LG UltraFine 4K for a Thunderbolt device and connect the Apple USB-C Digital AV Multiport Adapter to one of the USB only (non-Thunderbolt) USB-C ports of the LG UltraFine 4K.

The Apple USB-C Digital AV Multiport Adapter only supports up to USB 3.0 (5 Gbps). If you had a USB-C dock like the CalDigit SOHO which supports USB 3.1 gen 2 (10 Gbps) then connecting it to the Thunderbolt port would be better because the Thunderbolt port supports 10 Gbps USB.

Your BlueTooth adapter is probably USB 2.0 or USB 1.1 so it doesn't matter what port you connect it to.