The expression fields are formula fields when the apps are published. Try to login with a different user and install the published app. All of the benefits of expression field are not usable...
Works fine for me - I see no issue. Please open "Field View" page and compare "Field Type".
Sorry Pavel, indeed. I had an older version of the app. I have placed a check on overwrite when publishing, but these changes are not taken. Thanks for the feedback...