Could not insert another user

[innocube]

I am not sure since when this admin feature has been broken.
But recently I have found out that adding a new user is not possible with the following error although I have provided username, user email and password. Only way for me to add another user at the moment is add a user and import this collections to the current version.

Need to set a username or email [400]

Since this is an admin feature, it seems definitely a bug.
Please fix this bug so that I can manage users again through meteor-kitchen generated Meteor codes. Thank you!