Using Sidebar as an App User

I'm working on an integration that is using the preview and sidebar UI elements and is using App Users.  I can successfully obtain a lower scoped token for the app user and load the UI elements however the sidebar does not seem to operate as the App user the token is for.  So for example if I add a comment instead of it appearing as from "John Smith" the comment shows as "Document Collaboration Sandbox" which is the name of the sandbox.  Is it possible to have the sidebar function as the app user?  Note: the token appears to be valid since the UI loads and the file I tested the comments against is previewed.

Edit: I know the App user can view and comment on the file as I can login as that user via the UI and comment on the file.