Why was the implementation of flextime a negative experience for the management at ToKu?

When the management of ToKu, a Malaysian timber manufacturing company, decided to implement flextime for its production staff, Ann, the shift supervisor, pondered on that decision. Her boss, Mr. Tan, had hinted that he was willing to invest in moving the company forward and was particularly interested in increasing the morale of all its employees. For a time, she saw a boost in the employee morale, but productivity did not show much improvement.