As mentioned on the r/leagueoflinux subreddit no games can launch under WINE as of 9.20. I know Linux isn't officially supported but there is a passionate group of players who only play on Linux, myself included. I was very pleased to see that League ran well under WINE and haven't had any issues playing all summer. I hope this bug can get resolved soon either by Riot, WINE, or the Lutris AppImage maintainers.
I'm playing under Lutris but any WINE installation should work.
Steps to reproduce
1. Launch client under WINE
3. Launch any game mode. In this case, try practice tool.