HP OmniBook 5 — HDMI External Display Prevents Normal System Shutdown

Model: HP OmniBook 5 Laptop 16-ag1xxx

CPU: AMD Ryzen AI 7 350

GPU: AMD Radeon 860M Graphics

RAM: 16 GB

Storage: 512 GB

Firmware/BIOS: F.03

OS: Ubuntu 26.04.1 LTS

Kernel: 7.0.0-34-generic

Problem:

When an external monitor is connected to the laptop's HDMI port and shut down, the display goes black and it does not completely power off - power-button LED remains illuminated. When the HDMI cable is disconnected, the same shutdown procedure completes normally.

Any help would be greatly appreciated. Thank you.