Friends were just denied boarding on the Caribbean Princes for a 10 day FLL-FLL Panama cruise. They had both Passport Cards and birth certificates.  The ship says it is an "Open loop cruise" and requires a passport book. This was a once in a lifetime cruise for them.  This despite passport office and TA telling them it should not be a problem before leaving for the cruise.  The app even let them scan there card and gave them a green light. No amount of discussion seemed to matter. They are