That's definitely a bug, looks like there's something wrong with one of your singles or concerts. Please send me your save file at sadambober@gmail.com
Windows:
C:\Users\*username*\AppData\LocalLow\Glitch Pitch\Idol Manager\data\auto_save.json
C:\Users\*username*\AppData\LocalLow\Glitch Pitch\Idol Manager\data\manual_saves
Mac:
~/Library/Application Support/Glitch Pitch/Idol Manager/data/auto_save.json
~/Library/Application Support/Glitch Pitch/Idol Manager/data/manual_saves