Thanks for your effort in diagnosing this.
I have had problems a long time now as I went to 4.3 during EA.
I wondered why there were so few reports of issues, it turns out that I had turned off automatic download of MMS a long time ago. And now I got bit by this bug.
Have not been able to find a copy of jolla-messages-1.1.48.3-1.8.1.jolla.aarch64 but I’m sure my problem would be fixed with that as well.
For now I have change to allow automatic download.