I believe this is the same issue your colleague, Stella Zhang, also raised. The problem is that when you set the study duration as 12 days, the system considers exactly 12 days, i.e. 12 * 24 hours. But I guess you expected 12 complete days from the end of the registration dates.
To get this behaviour, you need to set the study to 13 days. But this will only impact future participants. For the past participants, you need to manually adjust their “End Date”, as explained in our documentation.
But in your case, as your study is already in the field, things will get a bit more complicated. When you change study configuration for a participant, you need to make sure they update their study right away. Otherwise, if they remain offline or disconnected from Ethica server, they may not receive your changes.
Another thing to consider is that you need to make sure you have properly configured your surveys’ triggering logics.
Overall, I suggest to carefully check the documentation and test everything before making changes to make sure the system behaves exactly as you expect.
Hope it helps,