Inviting a user to a team doesn't automatically add them to the team (BBCDEV-8201)

When I try to add a new member who doesn't have a Bitbucket account to a team, they are not automatically added to the team after they have created their account. In order for them to appear in my team I need to re-add them after they've created their account. Once this is done the outstanding invite still shows, even though they've already been added as a member of the team.