I have this problem using unity 2018.3.0 or 2018.3.2, Vuforia 8.0.10 and the last model target generator.
I tried with an empty project and in another project with all core samples.
the Vuforia model target database loads without errors.
I can see the Dataset in the inspector.
the license key is a developer one.
I tried also with unity 2018.2.19, vuforia 7.5.26.
it seems all dataset created with the new model target generator are corrupted, or something else..
I read some other posts talking about the .NET FP parsing problem, so I tried to reneame "." with "," in all XML.
I'd like to try with the old target generator but it has been removed for the dev portal.
only vuforia samples are working.
hope someone can provide a running solution.