Some time long ago, I banned the character 缠.I added the word 纠缠 today and was cramming the list just now. When it came up, I thought to myself that I remember the character 缠, but not very clearly, so I clicked on the magnifying glass to browse through other words that it's a part of. By chance I noticed that it says "banned" in all 4 study columns. Had I not seen this, I would just assume that this item will show up in my review queue, but it probably wouldn't because it's banned.
I think there should definitely be some sort of feature/function that alerts users if there's a banned item in a list they've just made. If not I'm going to unban everything I've previously banned and stop using that feature