Your system information

• Steam client version (build number or date): 1748301070
• Distribution (e.g. Ubuntu): SteamOS 3.8
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: AMD Z1 Extreme [Phoenix APU]

Please describe your issue in as much detail as possible:

When using a deck-uhid InputPlumber target set by steamos-manager on my Legion Go or my MSI Claw 8 AI+ A2VM, I noticed that I am missing the "Rumble" button in the Steam Controller tester. Example from my Legion Go:

However, rumble functionality works on my handhelds if I choose a non-deck-uhid target like Xbox Elite controller:

Steps for reproducing this issue:

1. On a Legion Go, launch gamescope-session on SteamOS Main
2. Go to the controller tester in Settings -> Controller -> Begin Test

You will notice a rumble button is missing

1. Run sudo inputplumber device 0 targets set xbox-elite
2. Go back to Begin Test

Now you will have a rumble button which works when pressed