Not sure if this is a bug or not, but at certain point all of my idols suddenly became depressed, at 0 mental stamina, or around that number (1-5) for no reason, concerts were going well, nobody complained, we had one girl who was caught with a boy but nothing happened, just some buzz, I tried to quickly recover and hired more new talents but they also got dropped to 0 mental stamina one or two days later. So either something serious went down and no one told me, or its kinda bugged out.