Did you try running
salt 'master*' state.apply ceph.salt-api
to see if you get a more specific error? The related files are in
/srv/salt/ceph/salt-api. Feel free to look through the sls files.
If the package failed to install, that would be one issue. If it successfully
installed, but the sharedsecret is not getting updated then that would be a
different issue. If the service is not starting, then that's another issue.