I experienced the same.
besides that, it seems that the timeout setting that Gnucleus is using to determine if a client is available is way to short, besides that it's not configurable manualy.
This resides to me on file with 22 hosts all to be timed out. Basicly, this happened to all my test downloads. None came true and 98% of the hosts found where eighter timedout or remotely canceled.
This thing needs some tweaks.

Another thing that I'm missing is simply a preselect list for media types. I like the filter part though.

Another annoying thing: When is a file put in the failed state? If so, why isn't it automaticly researching and retrying. Now you've got to manualy activate it again. That's a pain.