Viceroy must be feudal - when is this possible with pagan empire?

So I took a German Catholic king, made him secretly pagan, made him publicly pagan, and then made him an emperor. So he instituted the law of viceroyalty. I summoned some courtiers to his court but he could not make them viceroys because they were not feudal. I looked at the menu for one of his sons and the son could be made a viceroy; apparently his son was feudal even though he had been bred and raised as a pagan.

I tried giving the courtier a county. He became a count, but apparently he did not become feudal.

Is there any way to make a non-feudal character into a feudal character? I would imagine that giving him a landed title should have worked, but it didn't.