Hi @Tanya_Boone
Yes, you have to map the labels to a contiguous format like 0,1,2,3,4,5,6,7,8,9,10,11
The error appears when you compute metrics, so you can perform the mapping with output_transform for the metric:
from ignite.metrics import Precision

labels_mapping = {
    10988: 0,
    10995: 1,
    ...
}


def ot_map_labels(output):
    y_pred, y = output
    new_y = labels_mapping[y]
    return y_pred, y

precision = Precision(output_transform=ot_map_labels)

Hope this helps