agreement by proximity

The verb agrees with the subject. A nearer noun⁠—in an of-phrase, a relative clause, a parenthetical, or other adjectival construction⁠—does not control the verb: The list of demands is short, not are. In one of those editors who, who refers to editors, so the relative clause takes a plural verb: She is one of those editors who check every citation, not who checks. If the verb sits inside the of-phrase, the relative clause, or other adjectival construction, it agrees with the noun in that phrase or clause: a list of demands that are overdue.