Upgrade from 11.x to 12.1.x AND change group in SEPM

Hiya,

We have been testing a 12.1 SEPM to upgrade an 11.x client who resides in one group, export the installation package to be used with SCCM and install 12.1.  We want to change the group that the endpoint is in alongside the installation, but when we choose the option "Add clients automatically to the selecterd group" this does not work.  Only new clients seem to obey this setting.

Is there something similar for endpoints who want to upgrade their SEP version AND change groups?  It has to be done in 1 seamless function