Help, your artist didn't get a ticket? No worries! That's by design and they never do. We'll explain...
If you've sent out artist briefings, you might notice they don't include tickets. This is correct.
Where the regular crowd briefings contain people's e-tickets, the artist briefings do not. As a matter of fact, artists don't get entrance tickets at all.
This is a very conscious choice. Artists often consist of multiple people, e.g. band members, backup singers, dancers, etc. By having all those people check in with their names, a lot of troubles are avoided.
When checking these people in, you can simply type in their name at the artist handling screen of Mission control.
There's one exception. If you have added accreditation items to the event that require an extra ticket, those tickets will get added to the briefing.
This regards items for which you have explicitly said an extra ticket is needed. The use of these tickets are your own choice.