How to synchronize messages between iPhone, iPad, macOS
turning on message in icloud in ios 11.4 will help sync messages on iphone, ipad, macos, and increase protection for all conversations and attachments in the application, and helpRemedy The message is not synchronized with iCloud on iPhone
if your messages are not in sync with icloud, you can refer to the following solutions to troubleshoot and speed up the synchronization of message history with the cloud.