Anyone else having issues inputting their LATAM PASS number on their reservation?

I just booked a flight with my Details, which included my FFN. After booking, I tried to book a LATAM+ seat, but it's saying that I have to pay. I double checked my details on the reservation, my FFN is not attached to my name for some reason. One customer service agent gave me some lame response that I can put in my FFN 48 hours before departure, and a 2nd agent told me it may be an issue with the website. Is this a common occurrence?

Update: I just input my partner’s AS FFN on the same Itinerary and worked fine on the LA App. I don’t understand why I can’t put it my LA FFN for myself. Is LA playing a game here, or is there website really just screwed up right now?