For some reason Azureus and Transmission client think they are firewalled on my system... well, they aren't. Not by me anyway! This system sits on my LAN with the net connection shared by another box running IPCop. Port forwarding for this port (24385, TCP and UDP) is enabled on IPCop. It is the same port I used to forward torrent traffic to my previous system, which run the previous version of Mint... I had no trouble there.
This is actually behaviour I encountered previously, but was never able to find a solution or any help. It seems to affect exclusively Ubuntu or distros based on Ubuntu such as Mint... would anyone have a clue as to why this is happening?