I am working with the IPUMS CPS Monthly files as well as the NBER CPS Monthly files from 2013 to 2017. In the NBER CPS Monthly data, I noticed there is a sharp discontinuity in the number of hours worked starting in 2017 (total hours worked jumps by several orders of magnitude). This seems to be true when using the NBER weights pwsswgt, pwcmpwgt, and pworwgt (I did remember to divide by 10,000 for the implied decimal places). In the IPUMS CPS monthly data, I do not see the same discontinuity in hours starting in 2017 using the wtfnl weight.
I suspect I am forgetting about some data quirk. Can anyone explain to me why there is a discontinuity in hours for the NBER CPS Monthly but not in the IPUMS CPS Monthly? It would also be helpful to know where the IPUMS CPS variable WTFNL comes from (i.e. does it correspond to a specific weight in the NBER Microdata).