As a footnote to this and to help others to find this easier, I have edited the title and want to add a few points.
CT’s seem to work fine in standalone and even for users in parallel where they are targetting a 0W setpoint, but beyond that there clearly are issues.
Removing the internal meter loop on the slave unit helps with some of the displaying of data but breaks the grid setpoint.
I am of the view that CT’s shouldn’t really be supported or considered for parallel installations.
The EM does add cost, but it simply works.