Did this print a deprecation message to the console? It should’ve done, because we’ll be removing parentView access from PluginOutlet’s imminently. In fact, it’s so un-recommended that it should cause a warning banner to be shown to admins in the UI 
If you didn’t see any warnings, please let us know!
(parentView is part of Ember’s classic component system, which we’re moving away from)
If you want to access information from higher up in the tree, then it either needs to be passed as an argument to the Plugin Outlet, or you need to use one of the available services (like currentUser, or router)