Issues with ARFoundation Prev.6 1.1.0 and Post Processing 2.1.6 on 2019.1

Following an update of Unity to 2019.1, and updating ARFoundation to 1.1.0 and Post Processing to 2.1.6 packages, all the content disappeared leaving behind a pink triangle in the project scene of my project. Trying to build the project produced a set of errors related to Post Processing:

Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: '../StdLib.hlsl' at line 22 (on metal)
Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: '../Colors.hlsl' at line 23 (on metal)
Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: '../Sampling.hlsl' at line 24 (on metal)
Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: 'Distortion.hlsl' at line 25 (on metal)
Shader error in 'Hidden/PostProcessing/Uber': failed to open source file: 'Dithering.hlsl' at line 26 (on metal)​

The scene looks like this:



Despite the errors the project does run. The build when running on iPhone 8, iOS 12.2 looks like this:



Could this be related to my post processing profile being setup incorrectly? Or is this an bug?