Hello @TomS44526 ,
You'd need to actually send the email, in order to fully test it, since custom field content won't show in test sends. Even if it's just sending to a single-contact list where you're the only contact, if you have something for that field, it should populate in the dynamic link if you've set it up correctly.
If it's still not working in a live sendout, and you feel that you've set up the custom field dynamic link correctly between your "test" contact's info and the email, then I'd advise calling our general support for live troubleshooting.
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