Yes, a runner has 1 stop or reversal of direction once the lookback rule goes into effect.
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USA 8-7-T-3-A When a runner is legitimately off a base after a pitch or as a result of the batter completing a turn at bat, and while the pitcher has control of the ball within the eight foot radius of the pitchers plate, the runner may stop once then must immediately return to the base or attempt to advance to the next base.
C-1 A batter runner who rounds first base toward 2nd base may stop once, but then must immediately non-stop return to first base or advance non stop to 2nd base.
C-2 a batter runner who overruns fist base toward right field, turns left and immediately stops, must then return non stop to first base or advance none stop to 2nd base.
There are a couple more citations but continue on with the same basis. A runner may stop once and then reverse direction or continue on once the lookback rule is in effect. For example, runner on 2nd takes a lead after the pitch and begins to return to 2nd prior to the ball being returned to the pitcher. Pitcher now receives the ball in the circle, that runner still has a stop or reversal of direction since she was already moving prior to the lookback rule going into effect. If the runner had been standing still when the pitcher received the ball, then moved one way or the other now they are committed to which ever direction they chose to go.