When you copy from a Reddit comment or a Discord message, the code might have invisible line breaks (CR/LF characters).
Codes are generally stable, but specific versions (like the Cool Math Games version) may have limited features that cause issues with codes from the full GitHub version. idle dice import save codes work
If you are playing on a browser (itch.io, Kongregate), a corrupted local storage file can interfere with the import process. When you copy from a Reddit comment or