Anybody know how to unset shift-option (aka alt, on a Mac) <left> in markdown-mode? I've been trying (eval-after-load 'markdown-mode (local-unset-key (kbd "M-S <left>"))) and (eval-after-load 'markdown-mode (define-key markdown-mode-map (kbd "M-S <left>") nil)) to no effect. 😕

I mean, it's a Saturday night, isn't everyone reconfiguring their Emacs?

You need to quote the form that goes in eval after load.

That might be it.

And I think the key has to be M-S-<left > (note the extra hyphen)