Unfortunately, the reload data action for the button object works only if you are the owner of the Qlik Sense app (Qlik Sense SaaS). In our use case, a user (e.g. analyzer with space edit permissions) should be able to reload the application with changed data from an excel file.
As an app owner I can also just go into the data load editor to reload the app. Please make the reload data action available to other users as well.
Thank you
Christoph