In this game (3rd episode+) quite rare, but still there are bugs related to the "wrong" sequence of some quests, because of which triggers of certain events may not work. If such an error is massive and widespread, such bugs, as a rule, are quickly fixed by the developer within a few hours or 1-2 days (if the update is new). But judging by the fact that you were the first to encounter the problem of triggering this quest, I can assume that players have not encountered this problem much. In any case, to understand the reasons for the trigger not working, you need to examine the save file.
You should try just loading from an earlier save file when none of the quests in Steve's branch have been completed yet, wait until Sunday and send Monica to the right address on the map.