You broke being able to use the backbone button to access the app menu. Previously I would long press to access the app menu. I now have to sacrifice either the back button or start button which is not ideal.

Same problem with Backbone / Guide button.
It was working before the update.

Steam Support said that they're not 'able to provide in-depth troubleshooting for third-party controller issues such as this'.

I disabled the Steam Link Overlay for the moment, waiting for a fix one day.

Originally posted by RedOctane:

You broke being able to use the backbone button to access the app menu. Previously I would long press to access the app menu. I now have to sacrifice either the back button or start button which is not ideal.

This will be fixed in the next update, thanks!

Just updated and it work again.
Thanks ;)