I am working on a binary classification problem for which I am using the BCELosswithLogits and (since my data is imbalanced) the BinaryFocalLoss. To get the probability of the sample being positive, I apply the sigmoid function to the output of the model. However, even though I could improve my model from 68% AUC to 81% AUC, when I look at the predicted probabilities, they are always below 0.5. Am I doing something wrong?