Now that you mention it, I was working with arranger a lot a few weeks ago, and 2 or 3 times my T1 kick track got messed up. I wasn’t adjusting that track at all between my Parts, so I was surprised when it happened. I didn’t notice if my other atmospheric tracks were affected because I was more focused on my kick suddenly sounding like garbage 
When the kick got messed up, I thought maybe I accidentally changed OT parameters via CC from my Digitone. That was my first week with the DN, so I thought it was my own stupidity with MIDI settings or something. Now I’m wondering if something else related to Arranger was going on! I’ll keep an eye out for the issue and will contact support if I can figure out a consistent way to reproduce it.
A workaround for when this occurs is to be vigilant about saving your parts every time you’ve finished an edit you want to keep. When my kick got messed up, I was able to restore it by simply reloading the part.
Side note: Have you read Merlin’s Guide? It’s a great resource to learn more about the relationship between Parts/Banks/Patterns/etc.