Your system information

• Steam client version (build number or date): 1751405894 (also Steam Deck Beta/Stable)
• Distribution (e.g. Ubuntu): SteamOS, Arch
• Opted into Steam client beta?: Yes (also happens on Stable)
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: AMD (Steam Deck) and Nvidia

Please describe your issue in as much detail as possible:

When using Steam Input, L2/R2 inputs from controllers are not sent by Steam Input until some other button or axis has been pressed. No input from the triggers is seen at all by the launched program. Once any other button/axis is pressed, the triggers send input as expected. When Steam Input is disabled, this behavior is not present - the L2/R2 input is sent as expected from the very beginning.

I've tested with a custom Godot project printing out any axis movement at all - when using Steam Input, both L2/R2 axes report 0.0 no matter how much they are pressed, until any other button is pressed, at which point they will start to work as expected. Happy to provide the project files or a binary if it helps with debugging.

(This is a problem for a SteamOS-specific utility I'm writing, where R2 is often the first input a user would give).

This happens:

1. on both Steam Deck and desktop Linux
2. on Desktop Mode or in Gaming Mode
3. on both Stable and Beta clients

Steps for reproducing this issue:

1. Launch any controller testing/display program with Steam Input enabled.
2. Press only L2/R2 - no input is sent at all, nothing happens
3. Press any other button/axis (X/Y/Start/Select/R1, move the control stick, anything on the gamepad - mouse/trackpad or keyboard action won't do)
4. Press L2 or R2 again - input is sent as expected