Model Tracking not recognizing model

Hi,  I'm in process of developing AR app for Android using Vuforia and as a start of user experience there's suppose to be an option to scan an actual physical object with the app and therefore show a 3D model in the app with all internal modules (pretty much same as on the Vuforia Model Tracking Sample video) So I have a actual model (picture no. 1) and a related CAD model which I added to Model Target Generator, went through all steps and created, trained and exported a database, which I imported to Unity. Just to see if it's working I added simple cube as a child module for Model Tracking in Unity workspace (picture no. 2) and run the scene to test it. (picture 3) And unfortunately it's not detecting the model at all, doesn't matter the distance, angle, background or anything.  But as the object is I guess pretty complicated for the tracking, as it has a lot of free spaces, I tried with a more solid model, of JBL Flip speaker. Same procedure, same result, no detection... And here is my question - why it is not working?  And I missing something? In all tutorials I've seen there is pretty much only AR Camera, Model Tracking, object to be tracked and model which is supposed to show after tracking is successful  Is if about some mistakes in Model Target Generator (MTG)? The CAD models are missing the color (and there is no option to color them in the MTG), but all dimensions and views are set correctly (I tried both Guide View and Advanced View, but with Guided View it anyway shows that it would require training, I don't know why) Any help would be much appreciated :)