[UWP] Grouped ListView Header empty

[CarstenGruenzner]

Description

The group header of a grouped ListView is empty, even a correct DataTemplate is provided.

Steps to Reproduce

1. Compile and run the provided sample
2. Click on the "Fill" button

Expected Behavior

Each group should have a non empty header.

Actual Behavior

The header is empty.

Basic Information

• Version with issue: Xamarin.Forms 3.0.0.530893
• Last known good version: Xamarin.Forms 3.0.0.482510
• IDE: Visual Studio 2017
• Platform Target Frameworks:
  • UWP: 16299
• Nuget Packages:
  Xamarin.Forms 3.0.0
• Affected Devices:
  Windows 10

Screenshots

Reproduction Link

GroupedListViewIssue.zip