angular: rxjs/BehaviorSubject with rxjs/Subscription not working between two components unless its a child component

using rxjs/BehaviorSubject and rxjs/Subscription to communicate two components through a service like this:

Service (code related to the problem):

import { BehaviorSubject } from 'rxjs/BehaviorSubject'

private _clientModalActionSource = new BehaviorSubject<string>('')
modalAction$ = this._clientModalActionSource.asObservable()
public updateClientModalAction(action) {
   this._clientModalActionSource.next(action)
   console.log('sent')
}

Component A :

this._api.updateClientModalAction(id)

Component B :

import { Subscription } from 'rxjs/subscription'

private _subscription: Subscription
ngOnInit() { this._subscription = this._api.modalAction$.subscribe(res => {
   this.refreshModal(res)
   console.log('received')
})}

This is working perfectly if Component B is child of Component A, but if A is the root component and B is inside its <router-outlet> (or the opposite) nothing is being received to the subscription, I only get sent in the console. (without ‘received’)

Plunker

so unless I’m doing something wrong…

I’m submitting a … (check one with “x”)

[x ] bug report