Since we had Field Service Management added as an extra feature it has broken the ability to create tickets within FreshDesk and via our customer portal.
One thing I have noticed is that when you log a ticket from within FD, if you change the Category field to be not a requirement when logging or closing a ticket, the ticket successfully gets created.
This has all be changed since the new Field Service Management feature got added.
This issue may not have been caused because of using FSM. As, according to our records, FSM hasn't been enabled on your account. Our team will reach out to you to sort this out.