Okay so how many surveys don't have a submit option? At all? I was asked to enter a word before opening the link and at the end of the survey, but it's not ending the hit.
Is this another trick to avoid paying fees?
In some cases, not always, pages are timed. Like when it takes a minute for the double arrows to appear, to continue the survey. Sometimes it's the same with the last page, and the submit button. If you're asking if it happens frequently, that there's no submit button...no. If you have time on the timer, leave it open and message the requester. That would be my suggestion.
Actually, that's usually my suggestion. Sometimes requesters don't know their study is broken. I've gotten bonuses for letting them know.
If you post the HIT when asking, others could confirm if they're having the same issue. fyi
EDIT Or maybe hit 'Enter' after entering your word?