Run splits missing on activity app, but walk splits show up?

I recently bought the apple watch series 4, and have been running with it now for almost 3 weeks. When I drill down into my run workouts and try to activate the splits drop-down, only the first split shows up. This is true whether I use the workout app, Nike+ running app, or Strava. The weird thing is that splits DO show up when I do an outdoor walk.

My wife has a series 3, same watchOS, and her splits show up on her runs. What gives?