A month after this post I write my own C++ solution for gamepad cardinal navigation on game and UI mode, using enhancced input (just the code that fits my needs). I control the focus at all time and do not lose track of it. It is the best I could have done, learned a lot in the process and no longer depend on any plugin. I can say that the code for slate and UMG is rock solid when properly understood and works really well. I hope in future versions they maintain how things are done right now and just make an effort in providing better documentation.