I'm getting "nan" value for loss, while following a tutorial from the documentatin


I’m following the “Fine-tuning with Custom Dataset” tutorial for Question Answering on the SQuaD dataset tutorial: available here. I’ve copy pasted all the code shown in the tutorial step by step. However, when my model starts training, I don’t get the expected metric values for loss as I normally would, instead I get “nan”. Here is the output when I run the
model.fit(train_dataset.shuffle(1000).batch(16), epochs=3, batch_size=16)

Epoch 1/3
5427/5427 [==============================] - 4604s 848ms/step - loss: nan - output_1_loss: nan - output_2_loss: nan
Epoch 2/3
365/5427 [=>…] - ETA: 1:11:28 - loss: nan - output_1_loss: nan - output_2_loss: nan

I don’t know what is wrong, and I don’t think this output is what is supposed to be.

Would appreciate any help with this regard.
Thank you.