Future's Market Gold Loss Bug

When using Future's Market, if you walk past your nexus whilst in debt (-1 or less gold), you instantly lose 50 gold. As you pass the nexus you see a little -50 pop up next to your champ the way it does when you earn gold. I've seen it happen on multiple champs the past couple of days and it doesn't seem to occur when you're in the positive (0 or higher gold.)