It is not possible to add new users to a group using the administration panel.
When I select a group I see this link:
Which only allows me to see this (list + remove users)
It seems this new administration panel is quite buggy.
Solved! Go to Solution.
Looking at your LastPass account, it seems you have reached the maximum number of users currently allowed under the license agreement. Let me know if you want help increasing this limit.
Sorry I'm not quite sure where you're experiencing the trouble there. Are you able to create a recording / screencast of how you are adding the user to the group?