Hey guys so I thought I would share my story to see if others out there are seeing the same thing. I got a new XS max on Saturday, set it up as new, and plugged my phone in and of course on WIFI and let me messages download. Only to find out that some threads never loaded and the ones that did were missing a ton of messages since June. Since I had actually ordered another new phone I had another one so I decided to use the one that came in to try again and that phone is doing the same exact thing. the iMessage for iCloud toggle on the original phone has been on since apple released that feature and everything syncs fine to my Mac but for some reason syncs across iPhone devices are not working. I've already talked to a apple senior support about this and we tried a ton of troubleshooting and a ticket has been passed along to an engineer about this. Anyone have this issue? A fix?