for the API method:
it appears that the &modified_since parameter has no effect. I tried and duplicated the problem using the Test API functionality.
I am sorry that you're experiencing this problem. I have duplicated this issue on my test account, and once I confirm with other members of the dev team, will file a bug. You can track the bug here once it's created:
Thanks for flagging this in the community, we always appreciate that.
I'm still seeing this issue - any date specified in the past returns the full list of contacts in the list. 1 day ahead of current date returns 0.
Should note I tested with both the php-sdk, as well as the API tester and tried various time formats, as specified on https://developer.constantcontact.com/docs/developer-guides/supported-methods.html#dates
Thank you for reaching out to the API Support team here at Constant Contact.
The original issue reported here has been resolved. In testing this myself I was able to limit my results to only contacts modified after a specified date and time. You may be having an issue that is account specific or perhaps there may be something in your contact data.
So that we can best assist you, please email firstname.lastname@example.org directly with information about which list or call you are attempting to make. Since you are seeing the issue with our API Tester as well, please include the Request URI and Headers shown there in your email.
API Support Specialist