Has anyone ever in the history of Buddhism claimed that the phenomenal aspect of the storehouse consciousness is also permanent? Has anyone ever in the history of Buddhism claimed that the phenomenal aspect of the storehouse consciousness is also permanent?

I'm not asking if it's impermanent, but if it is also permanent. Usually the absolute aspect of the storehouse consciousness is said to be permanent


  The revelation of the true meaning of the principle of Mahayana can be achieved by unfolding the doctrine that the principle of One Mind has two aspects. One is the aspect of Mind in terms of the Absolute (tathata; Suchness), and the other is the aspect of Mind in terms of phenomena (samsara; birth and death). Each of these two aspects embraces all states of existence. Why? Because these two aspects are mutually inclusive... Since it has been made clear that the essence of all things is empty, i.e., devoid of illusions, the true Mind is eternal, permanent, immutable, pure, and self-sufficient; therefore, it is called "nonempty"


I hope so, and the storehouse consciousness of ordinary people also -- because I cannot see a reasonable way to believe it is just impermanent.
It's impermanent.  That's kind of the point.  You're supposed to empty your store house consciousness or, practically speaking, at least try to stop perfuming the seeds.   


  4
  
  The store consciousness is clear and undefinable.
  Like a great river, it is always changing.
  Neither pleasant nor unpleasant, when one becomes fully realized, it ceases to exist.
  
  ...
  
  29
  
  That is the supreme, world-transcending knowledge 
  Where one has no mind that knows 
  And no object that is known 
  Abandoning twofold grasping 
  The storehouse consciousness is emptied 
  
  30
  
  That alone is the pure, primordial reality 
  Beyond thought, auspicious, unchanging 
  It is the blissful body of liberation 
  The dharmakaya nature of the enlightened ones 
  
  From Vasubandhu's Thirty Verses


What's "left" when you've abandoned the karmic conditions of the store-house consciousness and the two fold grasping (i.e. grāha-dvaya - the grasping of the grasped and the grasper himself) is ultimately all that is truly unchanging or supramundane.  That said, I think it makes more sense to call what's left simply "unconditioned".  It isn't subject to the negative influence of ordinary defilements.  When you call it "permanent", I think it's too easy to fall into the trap of seeing it as a "thing" or a "self".