Hi @sonia_ml,
Thanks for the additional insights. To me, it looks like there are actually two issues:
1) The layer that is being used to import the building footprints from.
2) Matching the building footprints to the projects.
I'm confident that we will get this sorted out soon.
Regarding issue 1
For future buildings I am importing a Multipatch footprint scene.
What exactly do you mean by a "Multipatch footprint scene"? Are you trying to import the footprints from the associated feature layer of a 3D Object Scene layer? Does your future buildings layer only contain the building footprints that you'd like to import to your Urban Model or does it also contain other features?
Regarding issue 2:
The screen with the validation errors is displayed if there are footprints in the future buildings layer that cannot be matched to a project.
A potential reason is that the values in the "Project" field of the future buildings layer don't match the projects' "Join ID".
Please ensure that the values stored in what you configure as the "Project" field when importing the future building footprints are matching the "Join ID" values of your projects.
In case of further questions, please let us know.
Thanks.