Verified on CFME-5.7.1.0 & RHV-4.0.5
Checked the exact scenario, as in description.
After cluster change, refreshing the VM details page, the cluster field is updated correctly:
Cluster <new cluster>
Resource Pool <data center> for Cluster <new cluster>
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://rhn.redhat.com/errata/RHSA-2017-0320.html