My bet is on it being stuck in the SO or GL DTR, like Kevin and Jeff suggest. Also check that the transaction date is in the correct YEAR. Lastly, if this is a V2017SP1 or V2016SP4, there is a bug (and a fix) where the drilldown from the invoice to the GL doesn't work, but everything is posted correctly. Check out KB ID: 82873. I give you this info because we don't know where they see it (or don't see it) as ""not registering.