I created the issue.
Thank you for your advice about where to post!

  
      github.com/huggingface/transformers
  
  
    
  
	  
  

  
    
      Some unintended things happen in Seq2SeqTrainer example 33
    

    
      
        opened 
        
          
        
        Nov 30, 2020
      
      


      
        
          
          forest1988
        
      
    
  



  I posted this report in the HuggingFace Forum at first, but @BramVanroy kindly told me to post the report here instead...