New group created with _1

if ARM creates a group with _1 as a postfix then the original group is no longer managed by ARM. Or a group with the same name already exists. if you want to use the existing group without a new _1 group just set the permissions with this group and disable the group wizard.

Hi

I deleted the group wirthouth _1, and renamed the other one. ARM seems to be ok with it 

But I don't know why arm 'thinks' it no longer manages the former group.

Did you accidentally change the content of the "description" field?

It should look something like this:
8man://lD//\<path>//<somekindofID>

No didn't

but this issue is related to another one : sometimes ntfs right can't be set on shares from a synology nas through dfs. So arm group is created but not set to folder. when I then try to add new right to folder, arm recreate a new group, with _1 even if there is another one existing with the right ARM description field

This doesn't matter. The "issue" with _1 group creation is totally correct if there isn't a arm group set on this specific folder. So ARM has to create a permission group regardless if there exists one in the AD.

Did you check the arm server log for errors when you encounter this issue?

Did you check the arm server log for errors when you encounter this issue?