This may be a minor issue, but it appears to me that in the ACS Summary File Technical Documentation, the jam values for year structure built has not been kept up to date with the data, or the data erroneously includes values beyond the jam value.
On page 18 of the most recent documentation file, it shows a value of 2010 indicating "2010 or later" for year built. However, for the 2013-2017 5-year estimates, Maricopa, Arizona tract 9806 has a value of "2015+" on AFF, and 2016 in the downloadable summary files. Various tracts in other states have values between 2010 and 2016.
I'm not sure whether this is a documentation issue or a data issue. It does seem problematic to have a value that takes place midway through the survey period (though that question is hurting my brain a little).
Lastly, if jam values are changed, this would be very helpful to have included in the Table & Geography Changes pages.