Need Help: Elgato Camlink 4K (USB3.0) Passthrough Challenges in Proxmox VM (Ryzen 3700X, X570)

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Hello Proxmox Community,

I am reaching out for assistance with a tricky setup I'm working on. My goal is to pass through an Elgato Camlink 4K device (eventually two, but currently testing with just one) to a virtualized Ubuntu instance for OBS streaming. Despite various attempts, I'm stuck with an issue where the video output remains black, although audio is transmitted correctly.

System Specifications:

• CPU: AMD Ryzen 3700X
• RAM: 32GB
• Motherboard: MSI MPG X570 (with PCIe set to gen3)

Objective:

• To achieve passthrough of one (and eventually two) Elgato Camlink 4K devices to an Ubuntu VM.

Current Issue:

• The system recognizes the Camlink 4K (audio works), but the video output is just a black screen.

Troubleshooting Steps Taken:

1. Implemented USB passthrough both by specific device and by port.
2. Installed a PCIe USB card, passing the entire PCI card to the VM.
3. Tested all USB ports available on the system.
4. Minimized connected peripherals to just the Camlink, keyboard, and mouse.
5. Experimented with various Ubuntu versions and flavors, such as Pop!_OS, Linux Mint, and Elementary OS.

Additional Context:

• GPU passthrough is functioning properly.
• The Camlink is detected as both a webcam and under its name, but only shows a black screen (audio is fine).
• Direct booting into Pop!_OS (skipping Proxmox virtualization) works without issues.

I would greatly appreciate any advice, insights, or suggestions from the community to help solve this puzzle. Thank you in advance for your time and assistance.