The issue affects the superdate( function, too: Hours from 0 to 11 give correct results, superdate(date("3.1.2018"),time("12:00")) gives the wrong result 3597782400, and hours >12 are working well. (My date is entered in German format "DD.MM.YYYY".)
Fixed time( function so that it will correctly handle times from 12:00 to 12:59 (with no am/pm, so should be in 24 hour format). Fixes issue #821, and as Dave pointed out, this also applies to issue #401. It turns out when working on issue #401, I didn't quite fix it correctly, so this leftover bug remained.