Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain _03d548582a03ed91a974fb4ead04e682.content.product.axcient.com is not the root of its zone.
Instead, try zone transfer on mhbtsbpdnt.acm-validations.aws .
Instead, try zone transfer on mhbtsbpdnt.acm-validations.aws .