I'll probably fix it in the next update in a few days, but for now you should be able to fix it like this:
Open your save file with a text editor, find "SpecialEvents_Manager__EventData" and change "Status": 1 to "Status": 0
Win: C:\Users\*username*\AppData\LocalLow\Glitch Pitch\Idol Manager\data\manual_saves
Mac: ~/Library/Application Support/Glitch Pitch/Idol Manager/data/manual_saves