Need help with text syncing from phone upgrade

[sd4f]

I recently acquired a Lumia 950 to replace my L920 with.

Now i've been trying to set it up how I want, getting it updated, etc, and trying to maintain a fairly light experience. While i've been playing around with either loading a backup of my L920, or just going in vanilla, I've had issues with text syncing. I've noticed that my texts all sync to the L950 right up until I got it, i.e. 29th of May (last Monday). Because I was having some issues, I have still been using my L920, while I get things right on the L950.

Thing is, all the texts since Monday won't load, and it's annoying because I have been making a few. They're still on my old phone (the L920) and I've been trying to get them to sync across with forced backups and whatever, but nothing seems to be working.

Anyone know what I have to do?

 

[sd4f]

Ok, I've kind of resigned to having some texts get lost, but I've noticed that there's a whole series of tests from about February 2016 - February 2017 that have not synced over.

Does anyone know what you have to do to get this stuff to sync across? I tried another reset on my L950 last night, but nothing has changed.

This is starting to get incredibly annoying. I still have all the texts on my L920, and don't want to copy them across with the app for two reasons; first because it will double up most of the texts, second because it won't copy over mms.

This is starting to really look like a massive fail on MS part... I've been googling it everywhere, and a few people have had this problem with no fix.