I have seen multiple posts with the same question, but still no solution.
I have used the Android Object Scanner app, scanned and tested the target. Tests work well, and the target is detected in the app.
Downloading the .od file, creating a database, and downloading the Unity package version of the database into Unity, the object recognition never works. It works great with image targets, so is not a webcam or Vuforia issue.
I am using Unity 2019.3.0f1 and Vuforia is updated to 9.2.8. Again, testing in the Object Scanner app proves the object recognition is working. It is not in Unity.
There are no longer options to "activate" a database, they seem to just be added by default, and I assume activated by default?