IMPORTANT NOTE: Twitch Item drops and account linking with Twitch are currently on hiatus as we upgrade and migrate to the new version, and possibly make a few changes while we're in there. You can find more information regarding this on our forum post.
With how the Twitch Drops system works, you only earn the rewards on the account you linked to recently. For example, if you linked Steam to Twitch, and you watch streams, you earn the item drop on Steam. If you want to earn on console also, you would need to then link your Twitch account to your console Klei account and re-watch streams to unlock them on that platform.
If you would like to earn Twitch item drop rewards on Steam again, just link your Twitch account to Steam once more.