I know this doesn’t answer your question, but I have a similar scenario. The price of my May sailing went down quite a bit. I received a FCC from NCL, same as you. The weird thing is I had bid on upgrades before requesting the price adjustment. Now if I go and try and modify my bids, I can see them, but when I try to modify them it says “no eligible cruise found”. I have never seen that message before so I’m assuming because I got the FCCs it cancelled out my eligibility to bid. I’ll be curious to see what your experience is.