Steps To Reproduce:
On 19.3
1. Create a project
2. File > Build Settings > Player Settings > XR Settings
3. Select Vuforia

On 19.2
1. Create a project
2. File > Build Settings > Player Settings > XR Settings
3. Click on the vuforia link to download the package
4. Install vuforia and restart editor
5. Hierarchy > Vuforia Engine > AR Camera

Stack Trace: Assets/Vuforia/Scripts/DefaultModelRecoEventHandler.cs(59,24): error CS0234: The type or namespace name 'UI' does not exist in the namespace 'UnityEngine' (are you missing an assembly reference?)

Expected Result: Vuforia is enabled and all vuforia assets are imported

Observed Result: Error is thrown in the console

Reproducible On: 2019.3.0a3, 2019.2.0b2, 2019.2.0b1

Not Reproducible On: 2019.2.0a14

Environment: Win and Mac