Hi! Me and a few more people are trying to find a solution to one problem that occurs on IPhone. After importing a preset (dng) to Lightroom Mobile the dng file is 'empty', like there would be no preset saved on it. We have no idea how to fix it. There is many people with this problem. And this is for sure not a problem with the files. Its problem with Lightroom. Anybody knows how to fix it?
In this case like I said - after importing the file to Lightroom it has no settings on it to save. So after creating the preset the way you said - the preset has no settings. And it's not fault of the file like I said. And it's a problem of many people. Not just one case.
We have just released a version 6.2.1 with a fix. Since this was an import issue you need to re-import the dngs ---Let us know if its working for you now...and sorry for the trouble - Guido/ Lr Mobile QE