Given that Firewall is intended to prevent or manage network traffic entering a system and normally has no effect on signals coming from other sources including USB, check System Preferences > Network and see if your USB port is listed among the network ports and if so, try removing the USB port from the list of possible network ports (select it and click the minus sign (-) at the bottom of the list of ports) and see if that doesn't correct how it functions. It is easy enough to add it back later if you need to.
