Application User cannot set Application Id

I followed this guide for Dynamics 365 v.9.0:

https://msdn.microsoft.com/en-us/library/mt790170.aspx#bkmk_CreateAppUser

I successfully created the application user and assigned him a license, and a copy of a system admin role.

But whenever I switch to the application user form to set the application ID the app ID will always be set to blank after saving the record.

I did grant my application the right to acces Dynamics 365.

Any ideas why it does not work?