I only have one AppleID which I use to log into multiple devices all my other devices Messages works fine it's just stopped working on the iPhone 12. All images show a ? and the file name and the download symbol, I reset network settings on the phone which is annoying as I lost all my WiFi connections that worked for messages a couple of days old allowing me to manually download but new messages went back to not downloading.
It's looking much like I may have to backup and reset the phone not very impressed, I know it's probably the OS Apples software QA these days is as bad a Microsoft even my M1 Mac is flakier than earlier versions.