When copying the user's address from the Mac Ivory client, it adds invisible Unicode characters before and after the address. For example, "@user@mastodon.social" becomes "\u202a@user@mastodon.social\u202c". Visually, there is no difference, but it makes it impossible for the bot to locate the user.
Considering my limited knowledge of Python, I suggest using re to remove these Unicode characters before splitting the string.
100% proposition, 0% obligation.
Carlos Mañas