Safe zone overlay ignores alpha when set to 0.0 in DefaultEngine.ini.
Tested: 4.23.1 CL#9631420 , 4.25 CL#11341939
2. Launch as Standalone Game
Result: The transparency of the overlay does not respond to the set alpha of 0
Expected: The overlay to be fully transparent as shown in the documentation
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-89108 in the post.