In 2019, I am encountering this issue as well. I tried resizing the window and no luck....any other thoughts?
I am trying to create a web app with my new Enterprise account. I have worked with ArcGIS Online for over a year but this is my first attempt working with Enterprise, so perhaps I am missing something? There also seems to be an issue where the pop-ups don't inherit any of the configurations I made in the web map.
Best,
Katie
“The goal is not simply to ‘work hard, play hard.’ The goal is to make our work and our play indistinguishable.”
- Simon Sinek