there is a setting for number of downloads.
so if there are that many (it seems less actually) fetching metadata but not getting it then downloads on valid files are stopped.
to prevent this occasionally I need to go through those files which are perpetually and unsuccessfully trying to get metadata and stop them, then the other downloads, some of which were already partially achieved, start up immediately.
it appears that torrents are not working, but this is not the case.
I suggest that there is an option to timeout on fetching metadata and try later when other working torrents are completed.
I also suggest that there is a way to group those fetching metadata by progress bar, it doesnt do that at present.they need to be ctrol clicked and then right click to stop them. or do individually.
tixati 2.56, linux.

You can simply choose a higher number for max allowed downloads 10, 20 , 100...

go to settings->transfers->general

see where it says: 'Auto-manage slots'
check the box next to 'Downloads'

that way if a torrent is stalled and you have available bandwidth, Tixati will start queued torrents.