Help with UMG text field trigger virtual keyboard

Hey guys,
I am developing for Oculus Go and encounter this problem:
I have a 3D UMG Widget with an editable text box in it. I followed the tutorial here and had success However, I don’t want the keyboard to show up all the time, like in the tutorial. I only want to spawn the virtual keyboard the moment I click in the text box, but can’t make it work so far. What I have tried:

Has Any User Focus & Has Keyboard Focus to check whether the text field is focused, if so, then it will spawn the virtual keyboard. But it always returns false.
I have made sure that the 3d Widget that contains the text box is Window focusable, and the virtual keyboard is not focusable.

I have attached the image here for convenient.

Does anyone know how to solve this?

Thank you.