smart list reminder added to default non-smart list

I have a single smart list which contains items that don’t belong on any other of my reminder lists. They behaved as I intended until I updated my iOS to 18 a couple days ago. Now one of the items on my smart list is showing in another of my lists. When I try to change it back to the list i want the reminder on, it doesn’t update to correctly and stays in both of the lists. The list iOS is adding this to on its own is my default in settings. Very weird sing there are at least 20 other items that are not behaving this way. I even tried deleting the reminder & re-creating it.