About Parallel Projection Display

I’m a beginner who just started studying UE.
I want to check the viewport in parallel projection from above. However, when I select parallel projection, nothing is displayed in the viewport. Even if I scroll up and down, nothing is displayed. How can I make the screen look like the blueprint? As a side note, I was able to use parallel projection in other projects. There should be no difference in the settings, etc.
As for the level, it’s the minimum default for the starter content.