This is a known issue that has a internal ticket opened with 14.3 to be fixed.
Release : 14.2, 14.3
Component : CA IDENTITY SUITE (VIRTUAL APPLIANCE)
Please, to workaround this issue do these following steps:
1) Make sure you have a xml export as backup of task "IMRCM Create Active Directory Group". You will need this backup to restore this task after next steps.
2) Go to "Roles and Tasks" -> "Delete Admin Task" -> Search by "IMRCM Create Active Directory Group" and delete it.
3) Test again Endpoints -> "Manage Endpoint Groups" -> "Create Endpoint Group" for MS AD. At this point should work.
4) Import backup the backup you did in step 1 of xml export for "IMRCM Create Active Directory Group" and test again that should keep working.
A internal ticket is being worked to have the definitive fix under version 14.3. Check the published fixes for 14.3 if this is fixed or open a Support Case