Only reason I said it's safer to do edge down on sharpening is that it happened to a Bladesmith and I read about it in one of the Knife magazines in the 90s. He was out of business for a few weeks as the knife snagged on a belt and cut a tendon in his hand, not a buffing wheel (that happened too). I always use a light touch when doing the bevel anyway, but if establishing an edge on a new knife or fixing a really screwed up one I will start edge down and finish edge up, but as stated above by Crex, look at the condition of your belt, any frayed edges will snag the blade and the super fine micron belts are the most prone to snagging an edge up blade if there isn't any belt lube on them as they have a very thin backing. For 15 micron (1200 grit) I use Tap Magic applied with a rag, it also cleans them and makes them last longer. For sharpening I always use a fairly new belt. With my new 2x48 grinder I can grind backward and even if the belt snagged the knife, it would be flying away from me and not at my feet.
Wished I could find a 36" wet wheel like I learned how to grind knives on. It spun away from you and went through a water pan, so grind as hard as you wanted with it. Looked about 120/160 grit, but didn't say. Very old and made of what appeared to be Arkansas stone, probably started out as a 5' wheel and thrown away at 36". No markings and run with a winch motor and bicycle chain and sprockets. Was fast on the spinning circumference. Now that, I could make a hollow grind on, but shallow. My brother found it and set it up in his shop. Nice to have a sheet metal/blacksmith shop available. Would probably still be there if my brother weren't so crazy.
Oh I might add, a good medium diamond hone like my EZE Lap will sharpen a not too dull knife in a minute and my hand honing after grinding is only about 3 or 4 minutes. That diamond Hone takes it off pretty fast and I recommend them highly.