Shortly after releasing iOS 12.3, Apple has just released another update, iOS 12.3.1.
iOS 12.3.1 includes bug fixes for your iPhone and iPad. This update:
- Fixes an issue that could prevent making or receiving VoLTE calls
- Fixes issues in Messages that could cause messages from unknown senders to appear in your conversation list even though Filter Unknown Senders is enabled
- Fixes an issue that could prevent the Report Junk link from appearing in Messages threads from unknown senders
You can read about it here.