Message history not displaying on iPhone.

I recently did a full backup of iPhone from iTunes when getting a new phone.

Message history is not displaying despite settings > general > iPhone storage showing quite a bit of memory used up by messages (see screenshot below). All new messages are coming through OK.

Phone is synced to iCloud, which has more than enough storage available as it is paid iCloud, I have allowed a week to sync messages from iCloud- so it is not a case of waiting for download.

Things tried;

• restarted the message app
• force reset the phone
• turned off iMessage and back on again
• reset all settings to default