I have created a group and I want to add two survey administrators to it, but when I try, I get the message
Failed to add user.
User already exists in the group.
This is untrue. The user is not in the group.
Steps:
1. In Create/Edit User Groups, select my newly-created group from the drop-down.
2. Under Group Members (admin is already present) select an administrator, click Add User
3. Error message appears: Failed to add user. User already exists in the group.

How do I add administrators to a group?

LimeSurvey version? I don't have any problem with the latest (version 2.56.1).

Version 2.06+ Build 151215

I also have no problem in the latest version of 2.06 LTS. Please update and retest.

I can't update because it wants a paid account.
It is possible to add survey admins to a group in 2.06+ Build 151215 or is this a bug?