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 _b5c939eeb917fd7da88a70d4a3013ef1.bxmgrlxjqk.acm-validations.aws is not the root of its zone.
Instead, try zone transfer on bxmgrlxjqk.acm-validations.aws .
Instead, try zone transfer on bxmgrlxjqk.acm-validations.aws .