Simple HUD in Topdown template will have rendering errors if played in Immersive mode (F11). It will cause a white flickering line on the left and top of the window that will start to blur as the player moves around. A blurred box will appear in the center of the screen after a few seconds of moving.
Any rendering artifacts will disappear if the UMG widget is deparented. Additionally, the artifacts will only appear if the immersive-mode window is the only editor window being rendered. Opening any other window will fix the issue.
Results: A white flickering line will be present on the left and top of the screen. Move the character for several seconds more and you will see blurring/lens flare spread on the screen.
Expected: For Immersive mode to be identical to PIE or any other play mode.
Head over to the existing Questions & Answers thread and let us know what's up.