Use this to export your assets. The issue with Sketch itself and most other plugins is that it neglects invisible layers while exporting. As a result, invisible bounds do not work.
I even tried to decrease a bound's opacity to 0 so to try to trick Sketch into exporting it. But Sketch's native export isn't so naive.
You might see a horde of plugins of Sketch that help in exporting assets for Android easily. They might reduce the steps involved, but it doesn't solve the bounds problem.
This one does.
https://github.com/GeertWille/sketch-export-assets
It allows you to export assets for iOS, Android and Windows for all resolutions while keeping the bounds intact.
Saves all that artboard efforts.