This seems to only happen with the following cast setup:
- Quick Cast Setting for Ez-Throw Dynamite (W) set to “On”
- Begin holding the hotkey for Hero Abilities (Quick Cast on Release): Hero Ability 2
- Press the hotkey for Hero Management: Cancel Targeting
The ability will be cast, despite the hotkey for Cancel Targeting being pressed. The hotkey for Choose Ability or Talent Target does nothing in this setup.