Get Previous Scene: React native router flux (4.0.0-beta.28)

functions.js

import { Actions } from 'react-native-router-flux'

export function getPreviousScene (jumpCount = 1) { // if nothing is passed, it defaults to 1
  const index = Actions.prevState.routes.length - (jumpCount + 1) // because zero-based index
  
  if (index >= 0) {
    return Actions.prevState.routes[index].routeName
  }
  
  return 'home'
}

I used this approach because the provided prevScene erroneously returned the current scene for me.