Is there a reason Project Configurator would not import boards for a project?

[Rob Horan]

This is for Jira DC

I am assisting a team with project exports from one instance to merge to another, and in two test projects, the boards associated with those projects were not imported.

For one of the projects the boards were empty, but that wasn't the case for another.

Now, one thing to note is that for the import process, the option to update/modify existing objects was not used; all update items were de-selected. 

What could have caused this?  Could the boards simply not be associated with the projects? Is that possible with Data Center?  (forgive me if that's a dumb question)