`get_lmp()` for PJM fails to retrieve data for multiple node_ids

[claytonpbarrows]

from pyiso import client_factory
import pandas as pd
pjm = client_factory('PJM')

each of the two node id's requested independently return the correct results, but when combined, it only returns results for the first node id.

pd.DataFrame(pjm.get_lmp(start_at=datetime.strptime('2016-01-01 00 UTC', '%Y-%m-%d %H %Z'),
                         end_at=datetime.strptime('2016-01-03 00 UTC', '%Y-%m-%d %H %Z'),node_id=[40243837,32417577])).node_id.unique()

returns:

array([40243837])