Not able to map alt+backspace from external keyboard

Describe the bug
I am unable to map Alt/Option + Backspace/Delete from my external keyboard. Everytime I try to hold Alt+Backspace together, the shortcut recorder only captures the Backspace. If I do this on the laptop's attached keyboard, it registers it fine.

Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):
Macbook external (Windows) keyboard


Device information:

  • Type of Mac: Macbook Pro (2018 version)
  • macOS version: High Mojave
  • BetterTouchTool version: 2.660

Additional information (e.g. StackTraces, related issues, screenshots, workarounds, etc.):

Note: Before bug reporting, please make sure you have the latest version of BetterTouchTool and that you have already tried to restart your system :-). If you encounter a crash, please attach a crash log from the macOS from the "User Diagnostic Reports" section.