I would recommend to check the shapes of predictions (and all activations, which were used to compute predictions) as well as batch.label.
Since both should have the batch size in dim0, I assume you might be seeing this error in the last batch, which might be smaller?
This could explain the target batch size of 60, but wouldn’t explain the 66 for the predictions.
You could use drop_last=True nevertheless to remove the last and smaller batch.