Short answer. Often, yes. Article 84 of the Labor Code counts as hours worked all time an employee is required to be on duty or at a prescribed workplace, and all time they are suffered or permitted to work. If waiting for an assignment means being required to stay on duty or at the workplace, that time counts.
What the law says
Hours worked shall include (a) all time during which an employee is required to be on duty or to be at a prescribed workplace; and (b) all time during which an employee is suffered or permitted to work.
Labor Code, Article 84 — What Counts As Hours Worked. Read the full provision →
The two categories the article names
Article 84 defines hours worked as including (a) all time during which an employee is required to be on duty or to be at a prescribed workplace; and (b) all time during which an employee is suffered or permitted to work. Neither category requires the employee to be actively performing a task every minute. Category (a) is about being required to stay on duty or at a specific place, which by its own terms can include time spent waiting rather than working.
How this applies to waiting for an assignment
The key question the article points you to is whether you are required to be on duty or at the prescribed workplace while you wait. If your employer requires you to remain at the workplace, on call and ready to take an assignment, that waiting time falls within category (a) even though you are not doing any active task during it. The article's language turns on the requirement to be present and available, not on whether work is actively happening moment to moment.
Short rest periods during work hours also count
Article 84 adds a related rule: rest periods of short duration during working hours shall be counted as hours worked. This reinforces the same principle from a different angle — brief pauses that happen within your working hours are not carved out of paid time just because you are not actively working during them. It is a specific application of the broader idea that being required to be present, even without constant activity, still counts.
What the article does not spell out
Article 84 does not itself describe every possible waiting scenario or say exactly how "required to be on duty" is proven in a dispute. Whether a particular period of waiting genuinely involved being required to stay and be available, as opposed to being free to leave and use the time as you wish, is a factual question this article sets the framework for but does not answer for every case on its own.