My KTN almost always disappears when I go to check-in. I always add it in again so have never checked to see if it would give me pre check not adding it back in.

As I've said in other threads, I've encountered
Many problems with their website. I had problems booking when I try to add secondary contacts. Also, every time it has "use address on fuel" or the equivalent when I book online, it never populated the address and I have to add it in manually even with it checked.

It sucks when I have to enter the info for multiple travelers again so I no longer add contacts or do anything else in that page just in Case it messes up.