Im so sorry for wasting everyone's time with such a stupid mistake.
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As I see your goblin X vertices are all in same position (spawnX), so if your quad will be rendered with all X vertices in same position then it would be like a line. Try to add goblin width to v3x and v4x in goblin class, something like that:
public static int v3x = spawnX + 40;
public static int v4x = spawnX + 40;