I have a few more suggestions that you can try to resolve the issue:
1. Check for additional software updates: Go to Settings > General > Software Update to ensure you have the latest update installed, as there might have been a recent bug fix.
2. Reset Network Settings: Go to Settings > General > Reset > Reset Network Settings. This will reset all network settings, including Wi-Fi, mobile data, and VPN settings. You will need to re-enter your Wi-Fi credentials after this reset.
3. Sign out and sign back in to your Apple ID: Go to Settings > [your name] > Sign Out, and then sign back in with your Apple ID. This can help re-establish any connection issues with iMessage.
4. Disable and re-enable iMessage: Go to Settings > Messages and toggle off iMessage. Restart your iPhone, and then go back to Settings > Messages to toggle iMessage back on. This can sometimes fix glitches in the iMessage system.
5. Reset All Settings: If none of the above solutions work, you can try resetting all settings on your iPhone. Go to Settings > General > Reset > Reset All Settings. Note that this will reset all of your preferences and settings, but your data and apps will remain intact.