Emergency Bypass Bug iOS 15.4 - Not working

I have just upgraded to 15.4 on my iPhone 13. Emergency bypass for text messages no longer work. I have gone through all settings, tried out focus mode etc. and still have issues.

Emergency bypass works when:

• Screen is on, but message app is not open.

Emergency bypass does not work when:

• Screen is off
• Screen is on but messages app is open

I have not updated any settings since upgrade, so this appears to be a software bug. I have tried restarting my phone, running update again etc.