Do Not Disturb (Focus) not working properly on iOS 15

I have an iPhone 12 with iOS 15.5 and ever since the upgrade to iOS 15, the DND feature no longer works properly. Here's my current DND configuration and the issue I'm having:

Configuration for Focus > Do Not Disturb is:

Weekdays: 11:00PM - 7:00AM

Weekends: 12:00AM - 9:00AM

Issue: The DND feature properly activates at 11:00PM on weekdays and at 12:00AM on weekends. However, for both weekdays and weekends, it doesn't automatically deactivate and I have to disable it manually. I've tried deleting the DND automations and recreating them but this doesn't fix the issue. I've also tried adjusting the times a little (for example, 11:05PM - 7:05AM) but this doesn't fix the issue either. DND worked perfectly before iOS 15 (same phone).

So, because of the above issue, I've had to turn off my DND automations and I no longer use / trust the DND feature. Does anyone know if this is a known bug or if there's a fix?

Thanks!