Tixati isn’t forwarding ports. A few seconds after opening the main screen, a port forward under the name ‘Tixati’ appears on my router’s UPnP screen, but it vanishes in under one second.

Transmission forwards ports just fine, though.

I don’t know whether this info is relevant or not, but I’m running Tixati v2.58 64-bit over Windows 8, and my router runs dd-wrt v3.0 r33555.