Why is the TikTok repost button missing from one of my accounts?

TikTok documents Repost as an in-app option in the Share menu or the long-press menu, so first test it on a video from your For You feed in the mobile app, not just a shared link or desktop view. Make sure that account has the current app version, then check Profile > Menu > TikTok Studio > Account check (or Safety Center > Account check) for any notices. TikTok doesn't publish a switch that forces Repost back on, so if it stays missing only on that account after an update, use Profile > Menu > Settings and privacy > Report a problem and include a screen recording plus the account name. I'd avoid random region, VPN, or account-type fixes; they're mostly guesswork and can create a separate problem.