Hi again, may I wild guess?
because that is the only logical explanation I see
1. You are really talking about Groups (the topic above was about blocks, just the title and description just used the wrong vocabulary)
2. Your statement "I can add to the group " is not correct, you mean you can create a new group!?
Thanks to pendeans "Also.. start LIST command ", which led me to a test and indirectly to the following assumptions:
3. You are talking about existing group only? Draw two new circles, group them and ungroups works too?
What you do is: Object selection, contextmenu (rightclick) -> Group -> [Group] [Ungroup] [Add to Group] [Remove from Group] ?
4. Now, you have an existing group, you click on an object, the group is highlighted and you open the context menu -> Group
What you see is that just the first menu item available only: GROUP
(when you said "I can add to the group ", you mean this, what create a new group - not add an object to the existing group)
All three other context menu items are greyed out. Is this what you see on your side, is this your issue?
If so:
You selected objects who are members of two or more groups!
Greyed out, but the commands behind are still working well.
Try command: UNGROUP
Try command: GROUPEDIT option ADD
Try command: GROUPEDIT option REM
Also available in ribbon, start, Panel group
See also, the free help and product documentation [F1] for more information about Groups, group comm...