To reproduce:
1) Open attached project and scene
2) Play it
3) Click Bugreport->Open Test Code Window
4) Click "Capture Memory 'Editor'" Button

Expected: It reports a Native Array (you can see with Detailed Memory Snapshot made with profiler that it exists)
Actual: It reports nothing

Reproduced in 2018.1.0b2

The Detailed Memory view functions are on a different system than the Packed Memory snapshot when it comes to collected metrics. The Packed Memory Snapshot was not designed to directly collect native memory allocations instead it will only collect Types that inherit from Object (eg: GameObjects). While we will not be adding support for collecting native allocations to the current snapshot capture functionality we are working on a new system that will not have this restriction.