With October Update 2019 my Amazon remote is not working correctly anymore (with Pi 3b):
The menu button („hamburger button“) is not working anymore.
All other buttons are working correctly.
It‘s connected via bluetooth and is working for several updates - let‘s more than 2 years.
Have you tried using the keymap editor add-on to reprogram that button to the context menu (in keymap editor you would be programing global>navigation>context menu)?