I changed your code to use TPU, and other few changes e.g. setting Each_seq_length = 128 removing dropout to simplify the experiment.
On the first few epoch the loss indeed looks 0.2x-ish , but still decreasing. You can clearly see “overfitting” after epoch 8. So everything looks fine to me.
319/319 [==============================] - 148s 465ms/step - loss: 0.2118 - val_loss: 0.2075
Epoch 2/18
319/319 [==============================] - 66s 207ms/step - loss: 0.2062 - val_loss: 0.2024
Epoch 3/18
319/319 [==============================] - 66s 208ms/step - loss: 0.2046 - val_loss: 0.1902
Epoch 4/18
319/319 [==============================] - 67s 209ms/step - loss: 0.2022 - val_loss: 0.1905
Epoch 5/18
319/319 [==============================] - 67s 209ms/step - loss: 0.2004 - val_loss: 0.2246
Epoch 6/18
319/319 [==============================] - 67s 209ms/step - loss: 0.1994 - val_loss: 0.1829
Epoch 7/18
319/319 [==============================] - 67s 209ms/step - loss: 0.1866 - val_loss: 0.1857
Epoch 8/18
319/319 [==============================] - 67s 209ms/step - loss: 0.1639 - val_loss: 0.1929
Epoch 9/18
319/319 [==============================] - 67s 210ms/step - loss: 0.1417 - val_loss: 0.5679
Epoch 10/18
319/319 [==============================] - 67s 209ms/step - loss: 0.1123 - val_loss: 0.4180
Epoch 11/18
270/319 [========================>.....] - ETA: 9s - loss: 0.0942

You can see my modified colab here .

  
      
      colab.research.google.com
  
  
    

Google Colaboratory 44



  
  
    
    
  
  


Hope it helps!