To be hyper-precise, Score Mode causes the player 0/1 color circuits to be activated anyplace the playfield is active. When sprites have priority over playfield, this "covers up" the playfield color there. If playfield priority is enabled, the activated 0/1 colors get overruled by the playfield color, rendering score mode ineffective. Note that in score mode, the left half of the playfield has priority over the player/missile 1 sprites.