Right-clicking a group in the Symantec Endpoint Protection Manager (SEPM) and choosing "Copy Deployment Settings" pulls up a list of groups to which the selected group's install package configuration can be applied. Clicking the checkbox next to a group will select the group, however, clicking the checkbox on any additional group will deselect the prior selected group.
Multiple selection was disabled.
This issue is fixed in Symantec Endpoint Protection 14.2 RU1. For information on how to obtain the latest build of Symantec Endpoint Protection, see Download the latest version of Symantec software here.
To work around this issue please do the following after opening the Copy Deployment Settings dialog: