It is a very long one, but did not pay.
It's worth sending a note to Support. From Tom's chat, it sounds like they're changing vendors on some of the advertising, and this may extend to surveys. I think the chances of getting credit for it are slim, but if it's a vendor issue we want CN to be aware of issues..
The damned thing is I am so upset I completely forgot what the survey was... If it is not about a coding program or a house purchasing app, then it must be something similar. It was really long. But I will certainly know it if I see it again.
Surveys always credit for me. They do not always credit at the same time though. Sometimes they have credited before the close screen is closed and sometimes you have to wait until the next ad has credited.
If surveys usually credit for you then chances are it did and you simply missed it as it is quite easy to miss in the latest app. There is no +250 flashing any more.
If it didn't credit and you are sure then try support.
Kinda reminds me of the Pollfish surveys that I hate so much. I wish they would completely remove them or at least give us an option to not see then at all.
Never had one that I completed fail to pay off, which is probably no more than 10% - 20% of the ones I tried. The other 80% 90% all ended with the hated "Someone Ate The Surveys" message. Tried all sorts of demographic info when starting them but nothing changed the outcome. Even using the same info on the next survey after one of the few completed ones did no good.