I think there's an error in 'org-without-partial-completion' in org-macs.el.
The variable pc-mode gets bound to the value of partial-completion-mode - but
this is a VARIABLE (t if that mode is enabled). Funcalling the value of
the variable produces an error, unsurprisingly. This breaks insertion of
properties with 'org-set-property'.
Fixing it involves quoting the the symbol as shown below:
(defmacro org-without-partial-completion (&rest body)
`(let ((pc-mode (and (boundp 'partial-completion-mode)
'partial-completion-mode))) ; <-- quote added
(unwind-protect
(progn
(when pc-mode (funcall pc-mode -1))
,@body)
(when pc-mode (funcall pc-mode 1)))))
