Imo your much better off filtering at your gateway than trying to setup filtering on individual devices.
If your filtering at the gateway you know it's going to work and were to look if there is problems.
If there is a problem you've got one place to fix it, not 100's of individual devices and computers to tack down and attend to..
I would also recommend using a MDM solution to push out profiles, apps etc OTA
there are both free and paid solution, local hosted and cloud based
anyhow try clearing safari cache, restart the devices
First, I don't understand any of the jargon in the first half of your message. I'm a classroom teacher who uses the iPads in my classroom.
Second, I don't want to filter anything, but the iPad doesn't leave me with any choice. In Apple Configurator, I have to supervise them in order to restrict access to certain apps when testing, but if they are supervised, the content filter kicks in.
Third, the problem is definitely with iOS update. Another teacher uses a different cart on the same network, but she didn't update her iPads. Study Island is totally accessible.
Fourth, every time students get this silly restricted message, I immediately enter the URL into the accepted websites list in Apple Configurator and refresh the iPads. I clear the cache in both Safari and Chrome. Same result.
The problem is the design of the iOS, not the end user.
I miss understood your problem I thought you were choosing to use parental controls to filter
To simply what I was trying to explain about filtering.
The filtering at the network gateway is rather like someone at the gate of the school checking were each student is going when they leave and stopping those who are going to unsafe destinations
Rather than having someone in each classroom trying to stop students going to unsafe destinations
You tell the "gatekeeper" don't let the students go to xx
Instead of having to tell all the classroom minders and making sure they all understand
Anyway I digress, back to your problem
An relatively easy check you can carry out to find out if it is indeed a iOS problem or apple Configurator combo
Would be to unsupervise one of the iPads and see if you have the same issues
I'd have thought there would be many more complaints about supervised devices and blocking access
If that was the case
Nevertheless you could have discovered something with the combination of how you're doing things
If that's the case you'd better report your findings to Apple, who will hopefully fix the issue