Screen recording is not working

Just to clarify: on your point #2, using iOS 13 or later, the correct path is as follow:

Settings>ScreenTime>Content & Privacy Restrictions>Contents Restrictions>Game Center>Screen Recording.

Also, I would suggest the OP to read this support article:--> How to record the screen on your iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio

You may try these few basic tips and tricks if your iOS 12 screen recording is not working. Hopefully, one of these helps.

1.Confirm if Screen Recording is enabled

Go to Settings > Control Center > Customize Controls > Screen Recording, add it.

2.Restart Screen Recording and iOS device

Go to Settings > General > Restrictions > Game Center and turn off-screen recording, restart your device, and then turn Screen Recording on again.

3.Reset all settings

If the solutions above can’t fix the problem, then you can try resetting your iPhone. This method won’t remove any data from your iPhone. Simply go to Settings> General> Reset> Reset All Settings.

4.Upgrade to newest iOS version