The last track is the FX track, you’re right (the last of the 9 x mono tracks). I’m not sure why you’re not getting it through – you might need to go into the Overbridge control panel on your computer to enable it, I guess, but it’s only in mono anyway so it’s not that useful at all really! You need it in stereo, so you’ll have to mess with your voice routings on the DT.
Unfortunately, I just packed my DT up for a house move so my memory may be a little hazy, but IIRC to get the wet FX you need to go into the global settings (the cog button), and then go to voice routing. Switch off the routing to the main output for all of the tracks except the FX track. Then you can send the main output to another bus and record the FX by itself in stereo, while still getting all of the other tracks on their own channels. Hope that helps, if not I can try to give better instructions when I’m back set up at the new place