WAD Alt-Left doesn't work, but Alt-Shift-Left does

#1
The Help says Alt-Left will "Move the cursor left to the beginning of the argument (supports quoted arguments)." But, when I do Alt-Left nothing happens. Tried both the numeric keypad cursor key and the separate cursor key, both Alt keys and a standalone TCC and in a Take Command tab. However, Alt-Shift-Left works.

TCC 17.00.57 x64 Windows 7 [Version 6.1.7601]