Apple Intelligence download stuck at 100%

I am on macOS 26, M1 MacBook Air. I have been trying to download Apple Intelligence for days, but it is stuck at 100%; it just keeps loading. I have even left it to download overnight, but it is still stuck at 100%. Apple Intelligence is not working in any app. I have just turned it off, then on again; it started from 0%, like it hasn't downloaded anything. I see the issue has been reported on Reddit, but it seems there's no resolution for it.