https://wccftech.com/fallout-76-nukes-disabled-hotfix/

Fallout 76’s nukes are broken. I suppose that’s not a huge shock, considering the myriad of other problems the game has had, but still…you’d think Bethesda could get this one very big, very explosive thing right. Usually, Fallout 76’s nuclear silo codes reset ever week, but this week the codes were non-functional duplicates of last week’s codes. At first, players thought the messed up codes might have been related to an upcoming event, but it seems that isn’t the case.

Here’s some more info about the bug from Redditor Waffle Cop: