There are many reasons not to want to deal without wireless transmission, and your setup is one of the good ones!
Unfortunately, the Tread app is probably the only known solution for getting data onto the XT2 wirelessly.
So stay strong, and at least now you know that there may be problems with synchronization.
If nothing works while you're on the road, hopefully you'll also have the track available. (Displaying the track in the background is a great feature anyway, but I assume you already know that.)
And then if necessary, once you have the track, may delete everything from the XT2 and also in the Tread app, except for the tracks. (You may have to do this several times if deleted routes keep reappearing, but that's another issue.)
Then, to be on the safe side, create a route from the track on the XT2 or, for the fastest option, create a route from the track in the Tread app.
Finally, you may need to disable Bluetooth before or after sychronisation the route conversion (or only during routing).
Keep in mind that this is only one possible solution, as it has not yet been determined when or what exactly has negative effects.
Keep us updated and share your experiences.
(And may follow
viewtopic.php?t=2573)