It's time for today's question!
I created Action Script Assets to switch between three characters, and verified that they work through in-scene Hot Spot testing. I then created three Unity UI buttons and a panel to surround them. The panel is higher in the hierarchy than the buttons, but they are all direct children of the Canvas. The entire canvas is a prefab.
I created a new Menu in the Editor called "Character Buttons" and tied the prefab Canvas and Character Button Panel to it. I then created three Buttons, one for each character, and tied them to the pre-fab UI element and the Action Script Asset. I also generate button text with each character's name in the properties, as I deleted the text addition to the UI buttons.
When I run my game, the buttons appear and are clickable, but no text appears on them and they do not run the Action Script. I have tried may different configurations, but so far nothing is working.
Comments
Again, if you have a problem with a Unity UI Menu, always try switching the Source back to Adventure Creator to confirm that it all functions as intended in that way. From your description, it sounds like you've done everything correct (be sure to remove the UI from the scene, however), but it's not yet clear if the issue lies with the Menu Manager or with Unity UI.