Summary
Reported moths ago, but ignored.
If you create a widget with a Blur Background element, it won’t be visible if Corner Radius are higher than 0.
Reproduction project: https://drive.google.com/file/d/15t-XMwn6KVTzHflCjRLRDPtlEyBeMVip/view?usp=sharing
What Type of Bug are you experiencing?
Rendering (Graphics / Niagara)
Steps to Reproduce
Just open the provided project and Play as Standalone, or:
Create a Widget.
Add a Backgound Blur component.
Set a Corner Radius value higher than zero.
Add the widget to viewport.
Play in editor and notice it’s working fine.
Play as Standalone or in a packaged game, and notice how the blur component is not being rendered.
Expected Result
Widget component being visible.
Observed Result
Widget component not being visible.
Affects Versions
5.9
5.8
5.7
5.6
Platform(s)
Windows

