Cannot change Steam Controller layout after new Big Picture Mode

[That Linux Dude Dominic Hayes]

When attempting to change controller layout, the following occurs:
Big Picture Mode:
The 'layout' is the exact same as the current layout I want to replace, no matter what layout is chosen (on the rare occasion it does display the actual layout I want to replace it with, but even then it never applies it).

Normal Mode:
The window closes for literally no reason when you attempt to view a controller layout, 100% of the time.

This is on a Steam Controller - worked flawlessly before the update that introduced Steam Deck's Big Picture Mode, and I recall it also worked flawlessly on the Deck's own interface itself in pre-Deck-copied-Big-Picture-Mode Steam.

[Stoic]

I have the exact same issue with the Steam controller, since the recent major upgrade of Steam. I am not able to select a different layout (specifically from my earlier exports (from other games) with keyboard+mouse).
E.g., I would like to use the Assassin Creed II's layout (keyboard + mouse) in Assassin Creed Brotherhood. When selecting the AC2 layout, it basically goes back to the standard 'Gamepad With Camera Controls' layout.

[Babadook64]

Having the same exact issue here. Trying to use my ps4 controller to play skyrim, but want to use the keyboard mappings, only for it to crash and revert back to default every time I apply a new layout. Desperately waiting for a solution. :(