onBeforeRouteLeave is not called with named views

[ste-xx]

Version

4.0.0-rc.5

Reproduction link

https://github.com/ste-xx/vue-router-example

Steps to reproduce

Create View with two router-views.
One is named (e.g. toolbar), one is default.

The named view, used a shared component (e.g toolbar.vue).

The default view used different components. (e.g, home, home2)

Add onBeforeRouteLeave to the default view components.

E.g:

Add onBeforeRouteLeave to home.

Add onBeforeRouteLeave to home2.

What is expected?

onBeforeRouteLeave will always triggered if the route changes

What is actually happening?

onBeforeRouteLeave will not always triggered if the route changes.

[ste-xx]

Workaround:
wrap onBeforeRouteLeave in a onMounted.