USB devices attached to Ultrafine 5k display not activating

Number:rdar://34929774 Date Originated:11/11/17
Status:Open Resolved:
Product:macOS Product Version:10.13 (17A405)
Classification:Serious bug Reproducible:Sometimes
When connecting an external LG Ultrafine 5K display, USB devices attached to the display sometimes do not connect to the system. The devices need unplugging and reattaching before being recognised. I contacted LG support who said this is an issue with macOS and has apparently been reported to Apple. Apple support had no ability to help with this. Other users experience this issue in the discussions ( My display firmware is up to date. sysdiagnose attached captured when the display was connected with USB devices connected that were not recognised by macOS. This is not a hardware issue – both MBP and display have been replaced and have the same issue.

Steps to Reproduce:
Connect LG ultrafine 5k display with USB devices attached

Expected Results:
USB devices function immediately

Actual Results:
USB devices do not function until after reconnection


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