DickeFix, thanks for your additional work and clarification on this - hoping for some feedback from Buffalo on this one soon - I've spoken with several colleagues who purchased Buffalo NAS drives on my recommendation who are all currently experiencing the same problem, so this seems to be a global issue.
I tried your recommendations my end involving DHT but still couldn't get magnets to start, additionally I tried right clicking the file after adding and going to properties, however the full list of trackers was already present for me, each separated by a blank line. I tried to clear and re-enter this but the issue was still present.
I can confirm your suggestion of using Google or similar to search for the hash value to download the matching .torrent file works fine, good thinking there! Hoping Buffalo can come back with something though as it kind of defeats the purpose of supporting magnet links. :-)
Cheers,
Bobbo