It does fine until you reach around 20 mph then in locks the passenger front wheel in.

[2015 Z Force 800 53/Trail EPS]

Unless there is something really bad going on inside the diff, it can only be a problem with the wheel bearing and/or brake. My money is on the caliper not retracting causing the pads to drag and heat to a point of seizing. It can also be a loose bearing causing the brake to drag as well...just less heard of. Mine had rusted and seized slides..which were a bi*ch to fix. Inspect the rotor for any scaring or color that the others don't have, then pull it down for closer inspection. Also check that the brake peddle has enough play at the top that the rod to the master is loose, not tight as this will prevent the return port to line up with the res for fluid return.