Gitlab does not have features parity with Github. I personally also stumbled upon a bizzare bug that doesn't allow a friend to add me to any of his private repo's. Asked on IRC and nothing much came of it unfortunately.
Err... you're responding to someone who very clearly said they hit a (serious for them) bug which needs fixing. That's definitely not a feature proposal. :D
Which features would you like to see in GitLab? We'd love to talk about it. You could also open a feature proposal issues in https://gitlab.com/gitlab-org/gitlab-ce/issues.