Migrate rack ownership

Hi. Our DevOps supplier built our AWS based solution using Convox. Problem we now have is that we want to bring the management in-house but can’t identify how to transfer the rack ownership from one Convox account to another (their Convox account manages multiple clients so not possible to transfer it). There is an import rack feature but even though I have full AWS permissions I assume it doesn’t list because I didn’t create them originally. Any advice would be welcome!