My friend is trying to run a server in which he holds files and distributes them to use as torrents. Whenever we copy the magnet links, it gets stuck as hash link for us. He has trackers in the settings and he is running the swarms not set to private.

If you have trackers that announce individual peers (you see Peers=N, Seeds=Z in trackers tab) then you don't need to announce your torrents in DHT (the swarm). It's bad for privacy because DHT is public.
If you are stuck at retrieving hash (the most basic info about the torrent) then your computers cannot find each other OR connect at all. Check the peers tab if there's a timed out or 'waiting to connect' peer and observe the Event logs thoroughly. - notaLamer

When I start several magnet links in quick succession, and a few of them get stuck at "Hash link" / Fetching Meta Info. How can I reinitialize the torrents from tixati?