You have a tracked link in an email. When the email is received, the link breaks and doesn't redirect to the desired page. The link works perfectly when the tracking is disabled
The server hosting the link might not accept parameters, or might limit the number of characters in the parameter, etc. When tracking is enabled, Marketo adds mkt_tok=manymanycharacters. The issue could be either the page does not accept parameters at all, or does not accept such long parameters. You might need to reach out to the developers of that page and investigate this.
Our suggestion is to have “track link” checked but not the “Include mkt_tok”. Unchecking just Include mkt_tok will still allow the link to be tracked, but after redirect, the destination URL will not include the mkt_tok query string parameter.