The Chicago Traffic Tracker - Historical Congestion Estimates by Segment - 2018-Current dataset has not updated since 10/1/2018. We just became aware of the problem on 10/13/2018 and do not have an estimated fix time. We also do not know yet if the missing time slices will be recoverable or if there will be a permanent gap in the data.
We will update this post with any significant developments.
Update 10/18/2018, 12:30 pm: The dataset should now be up-to-date with little or no missing missing data, beyond the typical slight variations.