QuicKeys: Can't assign Enter or Tab as hotkey

Solution 1:

After much Googling, I finally found the answer in the user manual.

When the Hot Key assignment window appears, click and hold your mouse button with your mouse cursor in the hot key field, and press the Enter key on your keyboard while still holding the mouse button down. Clicking and holding the mouse button is necessary to assign some keys as hot key triggers; Enter and Tab are two examples of such keys.

This wasn't very intuitive when using the app. Really wish they had some sort of UI tip/hint pop up when trying to assign one of these 'special' keys as a hot key.