Issues with the group invite phrase

Hi! I’m experiencing some issues with the phrase groups.mail.join.invite. I want to invite users to our group where there’s an interesting discussion, and have been testing with my user - but the link in the email is broken and gives this error message.

When I send the same invitation from our sandbox, it works. I’ve tried copying the phrase from sandbox to live and then it breaks and gives the same error. Can someone help troubleshoot?

Thanks,

Stine