We've identified an issue that will cause project member invites to fail if the user is known to Tracker. Inviting members in bulk is also more likely to fail. We're working to correct this issue ASAP. As a workaround, it is necessary to paste the users entire email into the search field on the main Members page, then click the "Invite to project" link directly below that field. If you're still having issues, please contact us at firstname.lastname@example.org
with the email addresses of the users you'd like to add and the ID for the project(s) you'd like to add them to and we'll take care of it for you. Our sincere apologies for the inconvenience while we work to correct this.