Screen time turning off on its own

I have 5 iPhones and 3 are kids iPhones and the Screen time keep randomly changing or turning off. The screen time will show the corrector times but letting the kids use their phones past the time limits set. Why is this happening??? It was working fine about 14 months ago and thin just started bugging out. I can set a time and then mins or hours later it will just change on its own or turn off all together. I could say this is a software problem but it seems like an apple problem when it's all the phones. If this was just one phone I could see a download issue but it's not just one phone it all 3. This problem just keeps getting worse and worse. I need help to fix this what you recommend.