Is there actually a firewall between the 3300 and the PC?
When these kinds of issues are caused by a firewall, the person who is asked to check the firewall almost always frustrates the situation with "there is nothing being dropped by the firewall". And then weeks or months later, "oh, look, I didn't see those when I looked before".
Just temporarily put the PC on the same VLAN as the controller and disable the Windows FW to prove the point once and for all.