I'm using my own league as an example. https://www.lfs.net/leagues/412-Sport-Racing-Team-Finland

If there is a case, where multiple seasons are running at the moment, only one of them is shown at the Current Season-section; the other ones are shown at the Past, Present and Upcoming Seasons-section. I've attached screenshot of this.

Another thing, not a bug, but more like a request: one of my league's season (https://www.lfs.net/leagues/412/season/535) has races, but for each race, length is 0 laps at the moment. Why? Because at the moment, it's not possible to use minutes as a race length when adding/editing rounds for season. So, could it be possible to add minutes as a option for race length?

All active seasons are listed there now.

I'm not sure about your second request. The available settings reflect those that can be set in-game. And since there is no setting for minutes, it's not available in the league editor either. Do you sort of manually measure a race length in minutes?