"The employee is playing with you."
Translation:Der Arbeitnehmer spielt mit Ihnen.
Reporting is good.
I doubt that this will get changed, though, since this sentence was created by the Pearson cooperation and I don't think they ever check their sentences for reports.
See https://forum.duolingo.com/comment/24066422 for background.
So there's no point in new comments about how this "still isn't accepted". They will just clutter up the page but serve no useful purpose.
For the same reason "der Mitarbeiter" isn't accepted. I think of it as a matter of perspective: Mitarbeiter/in work for the same company you do, they literally work (arbeit) with (mit) you. Arbeitnehmer/in work for a company you're doing business with. In real life I might use Duo's sentence to describe someone who maliciously sent me to aisle 12 for a product she knows is in aisle 4.
der Mitarbeiter/der Angestellte = the employee
mit ihnen is not correct.
"with you" can be mit dir (if you're talking to one person whom you know well), mit euch (if you're talking to several people whom you know well), or mit Ihnen (if you're speaking formally, to one or more people).
Note the capitalisation in Ihnen.