I have setup linked mailboxes. I have one way trust.

I have created  universal distribution group. I have add owner to that distribution group. I have modify  default role assignment, so it is enabled : MyDistributionGroups-Default Role Assignment Policy, MyDistributionGroupMembership-Default Role Assignment Policy.

User that has linked mailboxes and is  owner of distribution group, can not see and of cores edit membership of distribution group.

Hi,

In your case, I recommend you use the following cmdlet to verify the distribution group owner at first.

get-distributiongroup -resultsize unlimited |ft name, managedby

What's more, you can add another mailbox as owner to check if this user can see the distribution group to determine whether the issue is related to the linked mailbox.

Best regards,

Well i run :

get-distributiongroup -OrganizationalUnit "OU=Company1,OU=Org,DC=RESOURCE,DC=COM" -resultsize unlimited |ft name, managedby

And i get  response :   under managed by : {RESOURCE.COM/Org/ Company1/User1}

Ser1 is disabled user and is linked to user in  account forest. 

And it does not work  in Outlook, so it is not  OWA issue

I have one way AD trust !