Campaign still sent to subscribers moved to another list


Our campaigns have the condition to move subscribers from one list to another upon clicking a specific link in the email.

Once the subscriber is moved, we'd expect that subscriber won't be receiving emails sent to the old list. However, this is not the case. We noticed many instances where the campaign to the old list was still sent to the subscriber in the new list.

When we checked those subscribers in the old list, we saw in the status that they were moved, and next to it we saw the date. But, after checking delivery logs of the campaign sent to the old list, we saw them being emailed even though they logically are no longer a part of the old list.

Why is this happening and how can we fix it?
My hunch is that they were sent because they were already queued for sending, in which case you can't stop sending them the email, but otherwise there's literally no chance for this to happen.