I intergrated a Landing Page with Constant Contact and tested it loads for the API feed into constant contact, all was fine. Went live with PPC campaign with landing page and initial 5 optins came into constant contact as new contacts without a problem. Next day beyond those 5 no new ones coming in, ran about 8 tests and no new contacts showing. I checked the API report and shows 25 calls overnight and only 5 contacts showing.
Anyone can help me find out whats happening?
After doing a bit of a dive into our logs, it looks like the API is returning an error 400 response. Since I'm not able to see the exact API requests, I don't know the precise cause. However, I suspect that it may be related to a change in the contact lists for the account. If the form was linked to a list that no longer exists, then the API call will fail as it's attempting to use a list that is no longer available.
If double-checking the list settings for the form does not resolve the issue, I would advise sending us an email to firstname.lastname@example.org with as much detail as you can, and we should be able to help you find some more information!