That a widget that take input and call event if that button we looking for. Backspace setuped for debug porpuses and its work fine, calling the event. But when i start build on Android system & use Back button, i didn’t get anything.
When i looked for answer i also tryed to use Enable Input & Set Input UI Only (as on screenshot below), but that don’t give anything to me.
I was having same issue on the blog. it seems like it was due to that i have reset the phone and some how it got fix. However, if you have same issue you should must visit this kodi addon post will give you high insights on it.