Vuforia OntrackingLost Function Doesn’t Work when Device tracker is Enabled?

I am facing the following problem: when I want to place an object in the Scene it moves around, I need it to stay in its place so it must be an anchor object.

Unfortunately, we can't anchor an object in Vuforia without Using Plane Ground detection.

Moreover after "Enabling Plane Ground Detection", the augmented object appear and never gets lost and the function "onTrackingLost" never triggered. It seems that this function is not automatically being Called and not working!

How can we solve...

Vuforia OntrackingLost Function Doesn't Work when Device tracker is Enabled?