When I cast some manzanita worthless wood using PR everything was great except the bark area never set. And I did use both vacuum and pressure. I ended up digging all the bark out of the rough-turned blank and filling with CA+ebony dust. Looked great in the end but what a PITA.
Do all wood types do this? No idea. But if you cast manzanita, make sure to remove all the bark. Either before you cast or after, your choice.
GK