Hey gents!
In terms of the 5.2.0 production version of the engine - we are still not able to run the template or even the AR session.
In terms of the 5.1.1 production version of the engine - my project buddy solved the black screen issue with the specific SDK/NDK settings. But the engine/ARCore is constantly yelling that there is a problem with these SDK/NDK settings. And still has several other stuff - like flipped screenshots - that make the version unusable in the AR context.
In terms of the 5.0.3 production version of the engine - it does work with specific SDK/NDK settings.
The version of the SDK/NDK - is 21.1.6352462.
I don’t believe we have much more time to tinker with these versions, but in case there will be any other options/solutions - will be keeping you posted, guys.