ARKit2 App rejected cuz of WorldMapping

"Thank you for your correspondence. We re-tested the app on an iPhone 7+ running iOS 12 and have found that we were still unable to get past the ‘Scan your Surroundings’ screen. We tested in a high-texture environment, very slowly, and were still unable to proceed past this screen. This 2.1 issue will need to be addressed before we can proceed with the review of the app."

So my app was rejected because I had to wait until a player "scanned his/her surroundings", meaning i did this:

    func session(_ session: ARSession, didUpdate frame: ARFrame) {
        if frame.worldMappingStatus == .mapped {
            os_log("MAPPED WorldMap")
            //do setup...
        }
    }

and looks like the AppStore review team couldn't get it to that point.

I use an ARWorldTrackingConfiguration.

I have literally no idea at all what to do. It works everytime for me....

ANY ideas are deeply appreciated!