I just had my first chance to test Idol Manager. I'm on Linux ( KDE Neon, Ubuntu 18.04-based ) but I suspect this is not Linux related. Apparently the game doesn't seem to support UltraWide screens very well:
Even though the option is offered on startup to select my native resolution ( 3440 x 1440 ). When I select a lower-than-native resolution and windowed mode, the game seems to start fine, so I'll just give it a go like that ;-)