I followed the 3 page tutorial here to get the current Display Name in an infopath textbox. https://spvee.wordpress.com/2013/04/10/auto-populate-user-information-in-infopath-with-claims-based-authentication-part-1-of-3/
After several tries I narrowed down the problem to something very specific.
It always shows the Display Name of the user used in the Credentials in the secure store service application. It doesnt use the current user.
I do have access to the farm, but I didnt not install it, so am not aware if something is wrong on IIS/App Pools or service applications.