@hf3gddJ8 - let's try this with a new test list, ignore what you previously had:
So, create a new list, empty, no subscribers.
Add a custom field NUM_OPENS with default value 0 and hidden.
Add a new segment called Without Opens where the condition is NUM_OPENS equals 0;
Create a new campaign, recurring to one day as you want. Make it send to this new list and to this new segment.
Make sure you set so that the custom field value increments by one on open, so set [INCREMENT_BY_1] for "Change subscriber custom field value upon campaign open".
Given the above, here's the logic to what is going to happen:
In day 1, a new subscriber is added to the list, it will get the value for the NUM_OPENS set to the default, that is 0. (make sure this is the case and that field is actually set to 0)
0 matches the segment Without Opens because the condition is "NUM_OPENS equals 0".
When campaign is sent, the subscriber will receive it because it matches the segment. Once he opens the email, the field value will increment by one, so instead of 0, it will be 1. Campaign finishes and duplicates itself for a new sending next day.
In day 2, a new subscriber joins the list, so right now you have a previous subscriber with NUM_OPENS=1 and a new subscriber with NUM_OPENS=0. When the campaign goes out, between these subscribers, just one matches the segment, the new subscriber. So the campaign is only sent to this subscriber and once opened, the custom field changes to 1 from 0 and the campaign duplicates itself for next day.
In day 3, if no new subscribers are added, none of the existing subscribers matches the segment, because all of them have a different value in NUM_OPENS than 0.
So that should do it...
Another aspect, please make sure "Custom fields sync" is enabled in Backend > Settings > Cron > Subscribers Settings.