The SceneName auto text tag only works for labels. You need the leader of the label to link the auto text to the model in the viewport. You don’t have to create a auto text field for labels anyway. It’s automatically available when you place a label with the leader attached to the model.
If you don’t want to see the leader you can edit it in Shape Style and make the Stroke transparent.
If you look at the items in the Scrapbook that include the SceneName tag you’ll see they work that way. If you drag in a label from the Scrapbook and drop it over the viewport so the leader(s) can attach themselves to the model, you can then just move the label where you want it and the leaders will remain attached.
