I discovered that when trying to insert a new item with a checkbox using M-S Return (org-insert-todo-heading), the keybinding is "translated" to M-Return (org-meta-return). As a result, all I get is simple list item without a checkbox.
M-x describe-key [Ret] M-S Ret ...shows the following... --8<---------------cut here---------------start------------->8--- M-RET (translated from <M-S-return>) runs the command org-meta-return (found in org-mode-map), which is an interactive compiled Lisp function in ‘org.el’. It is bound to M-RET, C-c C-x RET. (org-meta-return &optional ARG) --8<---------------cut here---------------end--------------->8--- A git bisect traced the source of this problem to the following commit: --8<---------------cut here---------------start------------->8--- 6965098a5357b09575a1119074545eb708cf5944 is the first bad commit commit 6965098a5357b09575a1119074545eb708cf5944 Author: Nicolas Goaziou <m...@nicolasgoaziou.fr> Date: Mon Jan 15 16:13:37 2018 +0100 Use a single keybinding representation * lisp/org.el (org-replace-disputed-keys): Fix docstring. Use `kbd' macro everywhere. Also add missing "ESC" equivalents for "M-" bindings. --8<---------------cut here---------------end--------------->8--- Thanks, Matt