Screen Time not working with Roblox?

I've set a screen time limit on my son's iPad Pro 9.7 to limit EVERY app to 20 minutes a day AND a specific filter for Roblox, but Roblox seems to be the only app that is not affected by this? Every other app has the hour glass and is grayed out except Roblox. This is very frustrating, as I don't mind my son playing games, but as long as I can control the content and time but don't understand why Roblox seems to be the only game immune to parental controls? The IOS is up to date and so is the app, I've restarted the iPad, deleted and reinstalled the app but everything I've done has been unsuccessful. Has anyone found a fix to this?