If I lease out a property to a tenant (apartment, retail, industrial use, whatever) and that tenant is committing an illegal activity on the property. Would the landlord be liable for knowing it? Or not?

"Sorry FBI, the tenant renting my warehouse out to manufacturing cocaine is not my responsibility. I won't do anything about it. You deal with them."

Nope, that's a failure of a duty to act and aiding and abetting a criminal activity if you hace constructive knowledge.