I took a few snaps in the coffee shop and decided to take a note of the file names.
As you can see above, the Leica iOS app can see the photographs on the camera and its seeing the correct file name. I downloaded the files to my phone and these were saved to the camera roll app.
I then launched Adobe Lightroom Mobile and imported the images, both jpeg and RAW as I shoot both.
As you can see while the meta data is correct but the file name has changed. So its not the Adobe app changing the name but likely something forced on the Leica app by iOS when it saves out to the camera roll app.