Unable To Send Modmail

When on the desktop website, using Old Reddit, every time I try to send a modmail using the "MESSAGE THE MODS" button on any subreddit's sidebar, I receive the error "RESTRICTED_TO_PM : User doesn't accept direct messages. Try sending a chat request instead."

How do I resolve this? My account has a fair amount of karma and it is several years old, everything I can find googling the issue only applies to new accounts and low-karma accounts?

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• RES Version: 5.24.8
• Browser: Firefox
• Browser Version: 141
• Cookies Enabled: true
• Reddit beta: false