Not sure if anything's
changed - I've had to call to take advantage of GG BUYUP before even when the website should have been showing me prices for a buyup. Since you're a 1K, maybe shoot them a call when you can and ask them to apply it for you? I just personally chalked this up to lovely old UA website issues, but maybe there's an underlying problem or trigger someone can point out.
Others don’t have the same experience I did that led me to believe that buyup and instrument supported upgrades are showing “online upgrade not available” at the same time for the same reason - thus probably best to ignore this answer.