Hi,
The problem persists. Am pretty sure it’s a glitch. And a similar one is showing itself on my phone.
All settings have been set by following instructions, phones have been switched on and off, downtime begins and ends at the correct set times, the allowed apps are visible but so is Snapchat on my daughter’s phone and so is Messenger on mine (I don’t have Snapchat to test it). Neither Snapchat on hers or Messenger on mine are in the allowed apps list yet both are usable in downtime. I think this is a problem that Apple need to be aware of so that when they update the iOS next, they can ensure that during downtime only the allowed apps are usable and no others can sneak in under the radar.