Your camera's clear flags are set to "Don't Clear". It should be set to "Solid Color", which is the default setting when you import the ARCamera. 

Hello,

This could be related to which process is controlling the device camera. When Vuforia is initialized, it will attach to the camera as a singleton. Technically, no other process can access or control the camera while Vuforia is running. The corollary is also true (from my understanding) that if another process is attached to the camera, Vuforia cannot access it and the video background from the camera feed will not be rendered. Normally, this results in a black screen being rendered when trying to run Vuforia.

My assumption is that Vuforia is controlling camera after app start and things work fine. However, when the app is backgrounded perhaps the native Unity takes control of the camera on resume?

I'm unfamiliar with the level of control provided by Unity native camera APIs. However, Vuforia provides APIs to control the device camera:

https://library.vuforia.com/content/vuforia-library/en/reference/unity/classVuforia_1_1CameraDevice.html

Perhaps you can use these (or Unity's) APIs to directly control the Vuforia camera during the app's lifecycle to insure "camera access collisions" do not occur.

Thanks,

Vuforia Engine Support

Hey Medabit,

I use the native unity camera with Vuforia Behaviour attached to it

Hello,

I didn't find many clues in the attached log, other than it looks like Vuforia crashed at some point.

Are you trying to use the native camera (Camera Game Object) in conjunction with the Vuforia ARCamera Game Object?

Thanks,

Vuforia Engine Support

Also something i forgot to mention,

We initialize Vuforia at the start of the app, however we have the Camera Game Object disabled at the start and only later when it is time to "Enable" the camera it self. Vuforia opens the camera correctly and the loaded markers work without a problem. and then when we disable the camera again, We go back to a "brown" screen. Touch input still works on the brown screen, it just seems to not render anything