Sorry, neither of us are ACF devs. You’d have to ask that of the dev team. https://www.advancedcustomfields.com/contact/
I haven’t actually used that plugin in a while, this was posted a long time ago. When I want to do this now I just use a select field that is dynamically populated with choices for menus that have been created (https://www.advancedcustomfields.com/resources/dynamically-populate-a-select-fields-choices/). I then code the template to show the selected menu using standard WP functions. The reason for this is so that I can do custom work that the plugin could not handle and the second reason is that I don’t like being dependent on 3rd party addons for ACF because of this very reason, you never know when the dev will stop supporting them.
