Afair camapign mythics appear in explore battles as soon as they are available from the paid campagn pass, but I’m not 100% sure about this.
Have you seen this lady in explore?
Plz call 555-Failed
I restarted the game 30+ times. Still missing her. 
She should also be seen here, doesn’t she?
I’ve encountered her last week, unless she somehow disappeared again she should show up.
That’s what I remember too as well as her picture showed up at the challenges button.
If someone would ping me on discord if they find her, I’d really appreciate it as I’ve slapped a little ‘may not be in explore’ note to the bottom of campaign graphics
