I’ve looked through the forum and see that this issue pops up a bit for Android devices, but I’m encountering this issue with my iPhone as I test Ethica. At first I get the notifications that a survey is waiting for me, but some hours later I stop receiving notifications. I have checked my iPhone settings and nothing seems out of order. It is set to use “persistent” notifications, and to “always” show. I can’t sort out what the issue is but I feel I need to have this sorted with my own device if I am going to trust it will work with participants.
In iOS, the app schedules only 40 notifications (both as “first notifications” and “follow-up reminders”). If the person receives these 40 notifications and does not open the app, the app does not prompt any further notifications. But if the participant opens the app, the app schedules enough more notifications so the total again becomes 40.
I suspect if you receive notification for sometime, and don’t tap on it, and after some point you do not receive notifications anymore, this can be the reason.
Hope it helps,