Keyboard Layout switching was set to Alt-Shift. After disabling "Keyboard Layout Options" >> "Key(s) to change layout", then Alt-Shift-Tab does display applications in reverse!
(I would still consider this a bug as both Alt-Shift and Alt-Shift-Tab are standards in other window environments [including older versions of Gnome/Ubuntu and MS Windows])
WORK-AROUND
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Keyboard Layout switching was set to Alt-Shift. After disabling "Keyboard Layout Options" >> "Key(s) to change layout", then Alt-Shift-Tab does display applications in reverse!
(I would still consider this a bug as both Alt-Shift and Alt-Shift-Tab are standards in other window environments [including older versions of Gnome/Ubuntu and MS Windows])