I noticed that 4.12 does not work this node, or rather its array always returns only one value of the first block collision in a single Trace node
The reason this isn’t working is because you’re using the Visibility channel and I assume that these boxes you’re trying to detect are blocking the Visibility channel instead of overlapping it. Once a Multitrace hits a blocking channel, it cannot continue hitting other things in that same path.
An easy way to explain this is to think about your vision being a line trace in the Visibility channel. You’re unable to see pass things that block your visibility, but if it’s something you can see through, like glass, you’re able to see things past it.
You can see an example here: https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/UseRaycasts/Blueprints/#multilinetrace