Is the primary group dynamic (memberOf attribute)? If so, SOGo doesn't support dynamic groups (see 0001324).

Hi Francis,

it is not a dynamic group

But the default group type when a group is created in AD Windows 2012 R2:
Group type: Security
Group scope: Global
Member of: access_sogo (this is the group all sogo users/groups need to be member of to have access to sogo)

E.g.
-) user user1:
member of: access_sogo, sogo_sharinggroup1, groupX, groupY, ...

-) group sogo_sharinggroup1:
Group type: Security
Group scope: Global
member of: access_sogo

-) group access sogo:
Group type: Security
Group scope: Global
member of: <empty>

SOGo dose not support nested groups.
No members in access_sogo, therefore no one to use.

Hello Christian,

access_sogo has members: all users + groups which need to access sogo.

It works when the primary group is not used to share:
e.g.
1) WORKS:
user2:
member of: access_sogo, group1, Domain User
primary group: Domain User
--> sharing of a calendar to group1 DOES work

2) DOES NOT WORK:
user3:
member of: access_sogo, group1
primary group: group1
--> sharing of a calendar to group group1 does not work

3) THIS AGAIN DOES WORK
user4:
member of: access_sogo, group1, primary-group-placeholder
primary group: primary-group-placeholder
--> sharing of a calendar to group1 DOES work

there no nesting deeper than "share to members of a group which is used in sogo" (but not "share to members of a group which is again member of a group which is then used in sogo")