Hi, I had that exact problem, and tried for several days to redeem MyPoints to UA. I messaged/emailed MyPoints & tried calling them. I’d never had a problem before & I knew my zip code hadn’t changed! So, I went into my United MileagePlus account, and I found that they’d added the extra 4 digits onto my 5 digit zip code. Once I changed my zip code in my UA profile back to the original 5 digit code, I was immediately able to redeem MyPoints for UA miles. Sounds simple, but it was VERY frustrating trying to figure it out. Hope this helps!