Issue in 'Run as' in App Data

I have a strange problem today. In my bubble editor, whenever I click ’ run as’ I am taken to index or some other page. Please help as I am unable to test my dev app. Thanks!

Please make sure you are not trying to run as with a reusable element in editor

Actually, I duplicated an existing app in dev. & used only a few of the components like the login page & workflow. I had created over 40+ users in the previous app which are now duplicated in the current app. Can it be rectified to work in the new app?