I had a galling issue with my gelding when I used a girth with elastic only on one side (made by thorowgood). I switched to one with a center stretch (made by wintec) and haven't had a problem since. I now ride in a dressage saddle and use a girth with elastic on both sides with no issues. All three girths are neoprene.
The material itself may not be the issue in your case, perhaps just the unevenness of the elastic. Worth a thought.