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 pmta-stage-edge-send4.sailthru-stage.cloud is not the root of its zone.
Instead, try zone transfer on sailthru-stage.cloud .
Instead, try zone transfer on sailthru-stage.cloud .