Cannot create a torrent-file under Transmission 1.77-1~bpo50+2

[James Brown <jbrownfirst@gmail.com>]

I probably find a bug  in the Transmission  1.77-1~bpo50+2: I cannot
create a torrent-file under it.
When I try to do that under its GUI, I cannot enter URL-adresses of
trackers: they don't save and disappear each time and I read that such
creating is failed.