Screen Time shows "Ignore Limit" on child's iPhone

I've updated our family's iPhones to iOS 12 and I'm using Screen Time to manage my kids' iPhone usage. Screen Time is pretty buggy which is no surprise since it's still early, but there's one issue that basically makes it totally ineffective for parental controls.

Normally when my kids try to open an app that's been blocked by Downtime (the schedule you set), there's a message that says it's blocked with a link to "Ask For More Time". But yesterday we noticed that when one of my kids opened up a blocked app the link said "Ignore Limit". This basically allowed her to open the app and use it with no restrictions. I restarted her iPhone by holding down the home and power buttons until the Apple logo appeared. I checked the blocked apps again and this time the restriction was working correctly. But there was one app that wasn't being affected by Downtime at all. I checked it this morning and somehow it's working correctly.

But this evening my other kid needed some more time with an app so I told her to request more time. She said she requested it but I didn't receive any request on my end. Turns out her Screen Time had the same issue where it was showing the link to "Ignore Limit". So I looked at her Screen Time settings and saw that "Block At Downtime" was turned off. I turned it on and it changed the blocked apps to "Ask For More Time". But her Messages app wasn't being affected by Downtime. I'm guessing it was because she ignored the limit? So I restarted her iPhone by holding down the home and power buttons until the Apple logo appeared. The Messages app is still available and now all blocked apps are showing "Ignore Limit".

Would appreciate some thoughts on a solution from others who might have come across this.