Raspberry Pi 5 PCIe Issue Resolution

I'm experiencing a problem with a PCIe switching device not enumerating on my Raspberry Pi 5 running Raspberry Pi OS.

Key Requirements:
- Expertise with Raspberry Pi 5 latest revision and PCIe devices
- Familiarity with Raspberry Pi OS
- Ability to troubleshoot PCIe enumeration issues
- Able to perform all work in a remote control session

Ideal Skills and Experience:
- Experience with Raspberry Pi 5 and PCIe configurations
- Strong troubleshooting skills
- Knowledge of device enumeration processes

I need an expert to help resolve this issue efficiently.
Exact same config and hardware is a known good config on another Raspberry Pi 5.