Ownership Plugin shows "unknown" in category row

Using the Ownership Plugin there is only "unknown" displayed in the "Primary Owner" column even though all jobs in the category have (the same) owner set.

Sadly I don't know if this is a fault of the ownership plugin or this plugin. maybe you can point me in the right direction so I can fix it myself.

Thanks for the great plugin! :-)

Reproduce the issue with the Ownership Plugin and a categorized view whose jobs share an owner. Start by tracing how the category row obtains and displays the Primary Owner value; done when the configured owner is shown instead of "unknown".

Written by the indexing model from the issue text.