Here is a snapshot of mine in Ultra for one of my races. So when you set up the race in Ultra, you are (pure guess here) setting it up as a 50K of whatever your distance is? But in ART, you are using miles? My guess is Ultra is showing the time results in how you set it up on Ultra. The output file from ART, (correct me if I am wrong Brian), doesn't export the distance. Time, Place, Bib, Name, age, gender, city, state, DOB, status. So Ultra is only filling in your times and other info and added them to the distance you have already setup. If you want it to show in miles in Ultra, you'll have to set it up as miles.
Each year for my races, I upload the times to Ultra for the rankings, then I also post them to my site with splits. I put a link in the race description in Ultra to the full results on my site. Hope that helps, Tim