Today, Twitch posted a blog outlining changes to their VOD system. While they are seeing improvements across the board, it comes at a price.
It means the Save Forever option is going away.
Going forward, all archives will remain for 14 days, then be deleted (60 if you're a Twitch Turbo user). Furthermore, any previously saved forever archives are being deleted in 3 weeks.
You have one of two options:
1. YT Export the archives (good luck, it's already down)
2. Pray you have local recordings like you should have done in the first place and migrate them to YT.
Consider this your warning to start moving things now.